S( n, m) = S(n-1,m-1) + (n-1) * S(n-1, m)
S( n, 1) = (n-1)!
S( n, n) = 1
S( n, n-1) = [n*(n-1)]/2

X = S(10, 7)

S( 2, 1) = 1! =   1                <--
S( 3, 1) = 2			   <---
S( 4, 1) = 6			   <---

S( 3, 2) = 3                       <---
S( 4, 2) = S( 3, 1) + 3 * S( 3, 2)
S( 5, 2) = S( 4, 1) + 4 * S( 4, 2)

S( 4, 3) = 6			   <---
S( 5, 3) = S( 4, 2) + 4 * S( 4, 3)
S( 6, 3) = S( 5, 2) + 5 * S( 5, 3)

S( 5, 4) = 10			   <---
S( 6, 4) = S( 5, 3) + 5 * S( 5, 4)
S( 7, 4) = S( 6, 3) + 6 * S( 6, 3)

S( 6, 5) = 15			   <---
S( 7, 5) = S( 6, 4) + 6 * S( 6, 5)
S( 8, 5) = S( 7, 4) + 7 * S( 7, 5)

S( 7, 6) = 21			   <---
S( 8, 6) = S( 7, 5) + 7 * S( 7, 6)
S( 9, 6) = S( 8, 5) + 8 * S( 8, 6)

S( 8, 7) = 28			   <---
S( 9, 7) = S( 8, 6) + 8 * S( 8, 7)
S(10, 7) = S( 9, 6) + 9 * S( 9, 7)

++++++++++++++++++++++++++++++++++++++++++

S( n, m) = S(n-1,m-1) + (n-1) * S(n-1, m)
S( n, 1) = (n-1)!
S( n, n) = 1
S( n, n-1) = [n*(n-1)]/2

X = S(20,15)

S( 2, 1) = 1! =   1                <--
S( 3, 1) = 2! =   2                <--
S( 4, 1) = 3! =   6                <--
S( 5, 1) = 4! =  24                <--
S( 6, 1) = 5! = 120                <--

S( 3, 2) = ( 3* 2)/2 =  3          <---
S( 4, 2) = S( 3, 1) +  3 * S( 3, 2)
S( 5, 2) = S( 4, 1) +  4 * S( 4, 2)
S( 6, 2) = S( 5, 1) +  5 * S( 5, 2)
S( 7, 2) = S( 6, 1) +  6 * S( 6, 2)

S( 4, 3) = ( 4* 3)/2 =  6          <---
S( 5, 3) = S( 4, 2) +  7 * S( 4, 3)
S( 6, 3) = S( 5, 2) +  7 * S( 5, 3)
S( 7, 3) = S( 6, 2) +  7 * S( 6, 3)
S( 8, 3) = S( 7, 2) +  7 * S( 7, 3)

S( 5, 4) = ( 5* 4)/2 = 10          <---
S( 6, 4) = S( 5, 3) +  5 * S( 5, 4)
S( 7, 4) = S( 6, 3) +  6 * S( 6, 4)
S( 8, 4) = S( 7, 3) +  7 * S( 7, 4)
S( 9, 4) = S( 8, 3) +  8 * S( 8, 4)

S( 6, 5) = ( 6* 5)/2 = 15          <---
S( 7, 5) = S( 6, 4) +  6 * S( 6, 5)
S( 8, 5) = S( 7, 4) +  7 * S( 7, 5)
S( 9, 5) = S( 8, 4) +  8 * S( 8, 5)
S(10, 5) = S( 9, 4) +  9 * S( 9, 5)

S( 7, 6) = ( 7* 6)/2 = 21          <---
S( 8, 6) = S( 7, 5) +  7 * S( 7, 6)
S( 9, 6) = S( 8, 5) +  8 * S( 8, 6)
S(10, 6) = S( 9, 5) +  9 * S( 9, 6)
S(11, 6) = S(10, 5) + 10 * S(10, 6)

S( 8, 7) = ( 8* 7)/2 = 28	   <---
S( 9, 7) = s( 8, 6) +  8 * S( 8, 7)
S(10, 7) = S( 9, 6) +  9 * S( 9, 7)
S(11, 7) = S(10, 6) + 10 * S(10, 7)
S(12, 7) = S(11, 6) + 11 * S(11, 7)

S( 9, 8) = ( 9* 8)/2 = 36          <---
S(10, 8) = S( 9, 7) +  9 * S( 9, 8)
S(11, 8) = S(10, 7) + 10 * S(10, 8)
S(12, 8) = S(11, 7) + 11 * S(11, 8)
S(13, 8) = S(12, 7) + 12 * S(12, 8)

S(10, 9) = (10* 9)/2 = 45          <---
S(11, 9) = S(10, 8) + 10 * S(10, 9)
S(12, 9) = S(11, 8) + 11 * S(11, 9)
S(13, 9) = S(12, 8) + 12 * S(12, 9)
S(14, 9) = S(13, 8) + 13 * S(13, 9)

S(11,10) = (11*10)/2 = 55          <---
S(12,10) = S(11, 9) + 11 * S(11,10)
S(13,10) = S(12, 9) + 12 * S(12,10)
S(14,10) = S(13, 9) + 13 * S(13,10)
S(15,10) = S(14, 9) + 14 * S(14,10)

S(12,11) = (12*11)/1 = 66          <---
S(13,11) = S(12,10) + 12 * S(12,11)
S(14,11) = S(13,10) + 13 * S(13,11)
S(15,11) = S(14,10) + 14 * S(14,11)
S(16,11) = S(15,10) + 15 * S(15,11)

S(13,12) = (13*12)/2 = 78	   <---
S(14,12) = S(13,11) + 13 * S(13,12)
S(15,12) = S(14,11) + 14 * S(14,12)
S(16,12) = S(15,11) + 15 * S(15,12)
S(17,12) = S(16,11) + 16 * S(16,12)

S(14,13) = (14*13)/2 = 91	   <---
S(15,13) = S(14,11) + 15 * S(14,13)
S(16,13) = S(15,12) + 15 * S(15,13)
S(17,13) = S(16,12) + 16 * S(16,13)
S(18,13) = S(17,12) + 17 * S(17,13)

S(15,14) = (15*14)/2 = 105	   <---
S(16,14) = S(15,13) + 15 * S(15,14)
S(17,14) = S(16,13) + 16 * S(16,14)
S(18,14) = S(17,13) + 17 * S(17,14)
S(19,14) = S(18,13) + 18 * S(18,14)

S(16,15) = (16*15)/2 = 120	   <---
S(17,15) = S(16,14) + 16 * S(16,15)
S(18,15) = S(17,14) + 17 * S(17,15)
S(19,15) = S(18,14) + 18 * S(18,15)
S(20,15) = S(19,14) + 19 * S(19,15)
S( n, m) = S(n-1,m-1) + (n-1) * S(n-1, m)
S( n, 1) = (n-1)!
S( n, n) = 1
S( n, n-1) = [n*(n-1)]/2

X = S(10, 7)

S( 2, 1) = 1! =   1                <--
S( 3, 1) = 2			   <---
S( 4, 1) = 6			   <---

S( 3, 2) = 3                       <---
S( 4, 2) = S( 3, 1) + 3 * S( 3, 2)
S( 5, 2) = S( 4, 1) + 4 * S( 4, 2)

S( 4, 3) = 6			   <---
S( 5, 3) = S( 4, 2) + 4 * S( 4, 3)
S( 6, 3) = S( 5, 2) + 5 * S( 5, 3)

S( 5, 4) = 10			   <---
S( 6, 4) = S( 5, 3) + 5 * S( 5, 4)
S( 7, 4) = S( 6, 3) + 6 * S( 6, 3)

S( 6, 5) = 15			   <---
S( 7, 5) = S( 6, 4) + 6 * S( 6, 5)
S( 8, 5) = S( 7, 4) + 7 * S( 7, 5)

S( 7, 6) = 21			   <---
S( 8, 6) = S( 7, 5) + 7 * S( 7, 6)
S( 9, 6) = S( 8, 5) + 8 * S( 8, 6)

S( 8, 7) = 28			   <---
S( 9, 7) = S( 8, 6) + 8 * S( 8, 7)
S(10, 7) = S( 9, 6) + 9 * S( 9, 7)

++++++++++++++++++++++++++++++++++++++++++

S( n, m) = S(n-1,m-1) + (n-1) * S(n-1, m)
S( n, 1) = (n-1)!
S( n, n) = 1
S( n, n-1) = [n*(n-1)]/2

X = S(20,15)

S( 2, 1) = 1! =   1                <--
S( 3, 1) = 2! =   2                <--
S( 4, 1) = 3! =   6                <--
S( 5, 1) = 4! =  24                <--
S( 6, 1) = 5! = 120                <--

S( 3, 2) = ( 3* 2)/2 =  3          <---
S( 4, 2) = S( 3, 1) +  3 * S( 3, 2)
S( 5, 2) = S( 4, 1) +  4 * S( 4, 2)
S( 6, 2) = S( 5, 1) +  5 * S( 5, 2)
S( 7, 2) = S( 6, 1) +  6 * S( 6, 2)

S( 4, 3) = ( 4* 3)/2 =  6          <---
S( 5, 3) = S( 4, 2) +  7 * S( 4, 3)
S( 6, 3) = S( 5, 2) +  7 * S( 5, 3)
S( 7, 3) = S( 6, 2) +  7 * S( 6, 3)
S( 8, 3) = S( 7, 2) +  7 * S( 7, 3)

S( 5, 4) = ( 5* 4)/2 = 10          <---
S( 6, 4) = S( 5, 3) +  5 * S( 5, 4)
S( 7, 4) = S( 6, 3) +  6 * S( 6, 4)
S( 8, 4) = S( 7, 3) +  7 * S( 7, 4)
S( 9, 4) = S( 8, 3) +  8 * S( 8, 4)

S( 6, 5) = ( 6* 5)/2 = 15          <---
S( 7, 5) = S( 6, 4) +  6 * S( 6, 5)
S( 8, 5) = S( 7, 4) +  7 * S( 7, 5)
S( 9, 5) = S( 8, 4) +  8 * S( 8, 5)
S(10, 5) = S( 9, 4) +  9 * S( 9, 5)

S( 7, 6) = ( 7* 6)/2 = 21          <---
S( 8, 6) = S( 7, 5) +  7 * S( 7, 6)
S( 9, 6) = S( 8, 5) +  8 * S( 8, 6)
S(10, 6) = S( 9, 5) +  9 * S( 9, 6)
S(11, 6) = S(10, 5) + 10 * S(10, 6)

S( 8, 7) = ( 8* 7)/2 = 28	   <---
S( 9, 7) = s( 8, 6) +  8 * S( 8, 7)
S(10, 7) = S( 9, 6) +  9 * S( 9, 7)
S(11, 7) = S(10, 6) + 10 * S(10, 7)
S(12, 7) = S(11, 6) + 11 * S(11, 7)

S( 9, 8) = ( 9* 8)/2 = 36          <---
S(10, 8) = S( 9, 7) +  9 * S( 9, 8)
S(11, 8) = S(10, 7) + 10 * S(10, 8)
S(12, 8) = S(11, 7) + 11 * S(11, 8)
S(13, 8) = S(12, 7) + 12 * S(12, 8)

S(10, 9) = (10* 9)/2 = 45          <---
S(11, 9) = S(10, 8) + 10 * S(10, 9)
S(12, 9) = S(11, 8) + 11 * S(11, 9)
S(13, 9) = S(12, 8) + 12 * S(12, 9)
S(14, 9) = S(13, 8) + 13 * S(13, 9)

S(11,10) = (11*10)/2 = 55          <---
S(12,10) = S(11, 9) + 11 * S(11,10)
S(13,10) = S(12, 9) + 12 * S(12,10)
S(14,10) = S(13, 9) + 13 * S(13,10)
S(15,10) = S(14, 9) + 14 * S(14,10)

S(12,11) = (12*11)/1 = 66          <---
S(13,11) = S(12,10) + 12 * S(12,11)
S(14,11) = S(13,10) + 13 * S(13,11)
S(15,11) = S(14,10) + 14 * S(14,11)
S(16,11) = S(15,10) + 15 * S(15,11)

S(13,12) = (13*12)/2 = 78	   <---
S(14,12) = S(13,11) + 13 * S(13,12)
S(15,12) = S(14,11) + 14 * S(14,12)
S(16,12) = S(15,11) + 15 * S(15,12)
S(17,12) = S(16,11) + 16 * S(16,12)

S(14,13) = (14*13)/2 = 91	   <---
S(15,13) = S(14,11) + 15 * S(14,13)
S(16,13) = S(15,12) + 15 * S(15,13)
S(17,13) = S(16,12) + 16 * S(16,13)
S(18,13) = S(17,12) + 17 * S(17,13)

S(15,14) = (15*14)/2 = 105	   <---
S(16,14) = S(15,13) + 15 * S(15,14)
S(17,14) = S(16,13) + 16 * S(16,14)
S(18,14) = S(17,13) + 17 * S(17,14)
S(19,14) = S(18,13) + 18 * S(18,14)

S(16,15) = (16*15)/2 = 120	   <---
S(17,15) = S(16,14) + 16 * S(16,15)
S(18,15) = S(17,14) + 17 * S(17,15)
S(19,15) = S(18,14) + 18 * S(18,15)
S( n, m) = S(n-1,m-1) + (n-1) * S(n-1, m)
S( n, 1) = (n-1)!
S( n, n) = 1
S( n, n-1) = [n*(n-1)]/2

X = S(10, 7)

S( 2, 1) = 1! =   1                <--
S( 3, 1) = 2			   <---
S( 4, 1) = 6			   <---

S( 3, 2) = 3                       <---
S( 4, 2) = S( 3, 1) + 3 * S( 3, 2)
S( 5, 2) = S( 4, 1) + 4 * S( 4, 2)

S( 4, 3) = 6			   <---
S( 5, 3) = S( 4, 2) + 4 * S( 4, 3)
S( 6, 3) = S( 5, 2) + 5 * S( 5, 3)

S( 5, 4) = 10			   <---
S( 6, 4) = S( 5, 3) + 5 * S( 5, 4)
S( 7, 4) = S( 6, 3) + 6 * S( 6, 3)

S( 6, 5) = 15			   <---
S( 7, 5) = S( 6, 4) + 6 * S( 6, 5)
S( 8, 5) = S( 7, 4) + 7 * S( 7, 5)

S( 7, 6) = 21			   <---
S( 8, 6) = S( 7, 5) + 7 * S( 7, 6)
S( 9, 6) = S( 8, 5) + 8 * S( 8, 6)

S( 8, 7) = 28			   <---
S( 9, 7) = S( 8, 6) + 8 * S( 8, 7)
S(10, 7) = S( 9, 6) + 9 * S( 9, 7)

++++++++++++++++++++++++++++++++++++++++++

S( n, m) = S(n-1,m-1) + (n-1) * S(n-1, m)
S( n, 1) = (n-1)!
S( n, n) = 1
S( n, n-1) = [n*(n-1)]/2

X = S(20,15)

S( 2, 1) = 1! =   1                <--
S( 3, 1) = 2! =   2                <--
S( 4, 1) = 3! =   6                <--
S( 5, 1) = 4! =  24                <--
S( 6, 1) = 5! = 120                <--

S( 3, 2) = ( 3* 2)/2 =  3          <---
S( 4, 2) = S( 3, 1) +  3 * S( 3, 2)
S( 5, 2) = S( 4, 1) +  4 * S( 4, 2)
S( 6, 2) = S( 5, 1) +  5 * S( 5, 2)
S( 7, 2) = S( 6, 1) +  6 * S( 6, 2)

S( 4, 3) = ( 4* 3)/2 =  6          <---
S( 5, 3) = S( 4, 2) +  7 * S( 4, 3)
S( 6, 3) = S( 5, 2) +  7 * S( 5, 3)
S( 7, 3) = S( 6, 2) +  7 * S( 6, 3)
S( 8, 3) = S( 7, 2) +  7 * S( 7, 3)

S( 5, 4) = ( 5* 4)/2 = 10          <---
S( 6, 4) = S( 5, 3) +  5 * S( 5, 4)
S( 7, 4) = S( 6, 3) +  6 * S( 6, 4)
S( 8, 4) = S( 7, 3) +  7 * S( 7, 4)
S( 9, 4) = S( 8, 3) +  8 * S( 8, 4)

S( 6, 5) = ( 6* 5)/2 = 15          <---
S( 7, 5) = S( 6, 4) +  6 * S( 6, 5)
S( 8, 5) = S( 7, 4) +  7 * S( 7, 5)
S( 9, 5) = S( 8, 4) +  8 * S( 8, 5)
S(10, 5) = S( 9, 4) +  9 * S( 9, 5)

S( 7, 6) = ( 7* 6)/2 = 21          <---
S( 8, 6) = S( 7, 5) +  7 * S( 7, 6)
S( 9, 6) = S( 8, 5) +  8 * S( 8, 6)
S(10, 6) = S( 9, 5) +  9 * S( 9, 6)
S(11, 6) = S(10, 5) + 10 * S(10, 6)

S( 8, 7) = ( 8* 7)/2 = 28	   <---
S( 9, 7) = s( 8, 6) +  8 * S( 8, 7)
S(10, 7) = S( 9, 6) +  9 * S( 9, 7)
S(11, 7) = S(10, 6) + 10 * S(10, 7)
S(12, 7) = S(11, 6) + 11 * S(11, 7)

S( 9, 8) = ( 9* 8)/2 = 36          <---
S(10, 8) = S( 9, 7) +  9 * S( 9, 8)
S(11, 8) = S(10, 7) + 10 * S(10, 8)
S(12, 8) = S(11, 7) + 11 * S(11, 8)
S(13, 8) = S(12, 7) + 12 * S(12, 8)

S(10, 9) = (10* 9)/2 = 45          <---
S(11, 9) = S(10, 8) + 10 * S(10, 9)
S(12, 9) = S(11, 8) + 11 * S(11, 9)
S(13, 9) = S(12, 8) + 12 * S(12, 9)
S(14, 9) = S(13, 8) + 13 * S(13, 9)

S(11,10) = (11*10)/2 = 55          <---
S(12,10) = S(11, 9) + 11 * S(11,10)
S(13,10) = S(12, 9) + 12 * S(12,10)
S(14,10) = S(13, 9) + 13 * S(13,10)
S(15,10) = S(14, 9) + 14 * S(14,10)

S(12,11) = (12*11)/1 = 66          <---
S(13,11) = S(12,10) + 12 * S(12,11)
S(14,11) = S(13,10) + 13 * S(13,11)
S(15,11) = S(14,10) + 14 * S(14,11)
S(16,11) = S(15,10) + 15 * S(15,11)

S(13,12) = (13*12)/2 = 78	   <---
S(14,12) = S(13,11) + 13 * S(13,12)
S(15,12) = S(14,11) + 14 * S(14,12)
S(16,12) = S(15,11) + 15 * S(15,12)
S(17,12) = S(16,11) + 16 * S(16,12)

S(14,13) = (14*13)/2 = 91	   <---
S(15,13) = S(14,11) + 15 * S(14,13)
S(16,13) = S(15,12) + 15 * S(15,13)
S(17,13) = S(16,12) + 16 * S(16,13)
S(18,13) = S(17,12) + 17 * S(17,13)

S(15,14) = (15*14)/2 = 105	   <---
S(16,14) = S(15,13) + 15 * S(15,14)
S(17,14) = S(16,13) + 16 * S(16,14)
S(18,14) = S(17,13) + 17 * S(17,14)
S(19,14) = S(18,13) + 18 * S(18,14)

S(16,15) = (16*15)/2 = 120	   <---
S(17,15) = S(16,14) + 16 * S(16,15)
S(18,15) = S(17,14) + 17 * S(17,15)
S(19,15) = S(18,14) + 18 * S(18,15)
S(20,15) = S(19,14) + 19 * S(19,15)
S(20,15) = S(19,14) + 19 * S(19,15)
