a(N,k) tabf head (staircase) for A092078 W. Lang, Mar 19, 2004 N n,m |k: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 1 1,1 | 1 2 2,1 | 1 3 2,2 | 1 | 0 4 3,1 | 1 5 3,2 | 0 | 1 6 3,3 | 1 | 0 | 0 7 4,1 | 1 8 4,2 | 1 | 1 9 4,3 | 0 | 1 | 0 10 4,4 | 1 | 0 0 | 0 | 0 11 5,1 | 1 12 5,2 | 0 | 2 13 5,3 | 0 | 2 | 0 14 5,4 | 0 | 1 0 | 0 | 0 15 5,5 | 1 | 0 0 | 0 0 | 0 | 0 16 6,1 | 1 17 6,2 | 1 | 2 18 6,3 | 1 | 1 | 1 19 6,4 | 0 | 1 1 | 0 | 0 20 6,5 | 0 | 1 0 | 0 0 | 0 | 0 21 6,6 | 1 | 0 0 0 | 0 0 0 | 0 0 | 0 0 22 7,1 | 1 23 7,2 | 0 | 3 24 7,3 | 0 | 3 | 1 25 7,4 | 0 | 2 0 | 1 | 0 26 7,5 | 0 | 1 1 | 0 0 | 0 | 0 27 7,6 | 0 | 1 0 0 | 0 0 0 | 0 0 | 0 | 0 28 7,7 | 1 | 0 0 0 | 0 0 0 0 | 0 0 0 | 0 0 | 0 | 0 29 8,1 | 1 30 8,2 | 1 | 3 31 8,3 | 0 | 3 | 2 32 8,4 | 1 | 1 1 | 2 | 0 33 8,5 | 0 | 1 1 | 1 0 | 0 | 0 34 8,6 | 0 | 1 1 0 | 0 0 0 | 0 0 | 0 | 0 35 8,7 | 0 | 1 0 0 | 0 0 0 0 | 0 0 0 | 0 0 | 0 | 0 36 8,8 | 1 | 0 0 0 0 | 0 0 0 0 0 | 0 0 0 0 0 | 0 0 0 | 0 0 | 0 | 0 etc. N n,m |k: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 Cf. Abramowitz-Stegun, pp. 831-2 Example: a(18,1) = a(18,2) = a(18,3) = 1: All three partitions of 3 appear once as exponents of partitions of n=6 into m=3 parts. Namely: (3) in [2^3], (1,2) in [1^2,4^1], and (1,1,1) in [1^1,2^1,3^1]. Proposition: binomial(n-1,m-1) = sum(a(N(n,m),k)*m!/product((m^{(k)}_i)!),k=1..p(n,m)), where p(n,m) is the number of partitions of n into m parts, and the product is over the parts of the k-th partition of m in the Abramowitz-Stegun order (see the A036040 W. Lang link). Proof: From the multifactorial representation of the Lah numbers A008297 (which constitute a Jabotinsky triangle (cf. A039692)) and their explicit formula. Examples for the Proposition: n=5, m=3 (N=13): 2*3!/(1!*2!) = 6 = binomial(4,2). n=6, m=2 (N=17): 1*(2!/2!) + 2*(2!/(1!*2!)) = 1 + 4 = 5 = binomial(5,1).