OFFSET
0,8
FORMULA
Let b(n,k) = 0^n if n*k=0, otherwise b(n,k) = (-1)^n * k * Sum_{j=1..n} (-n+k)^(j-1) * binomial(n,j) * b(n-j,3*j). Then A(n,k) = b(n,-k).
EXAMPLE
Square array begins:
1, 1, 1, 1, 1, 1, ...
0, 1, 2, 3, 4, 5, ...
0, 9, 20, 33, 48, 65, ...
0, 43, 140, 297, 520, 815, ...
0, 125, 1080, 3189, 6800, 12285, ...
0, -6279, -3568, 18003, 70464, 168125, ...
PROG
(PARI) b(n, k) = if(n*k==0, 0^n, (-1)^n*k*sum(j=1, n, (-n+k)^(j-1)*binomial(n, j)*b(n-j, 3*j)));
a(n, k) = b(n, -k);
CROSSREFS
KEYWORD
sign,tabl
AUTHOR
Seiichi Manyama, Jun 16 2025
STATUS
approved
