OFFSET
0,8
FORMULA
A(n,0) = 0^n.
A(0,1) = A(1,1) = 1; A(n,1) = 2 * Sum_{j=1..n-1} A(j,1) * A(n-j,j).
For k > 1, A(0,k) = 1; A(n,k) = (1/n) * Sum_{j=1..n} ((k+1)*j-n) * A(j,1) * A(n-j,k).
EXAMPLE
Square array begins:
1, 1, 1, 1, 1, 1, ...
0, 1, 2, 3, 4, 5, ...
0, 2, 5, 9, 14, 20, ...
0, 12, 28, 49, 76, 110, ...
0, 116, 260, 438, 657, 925, ...
0, 1488, 3256, 5352, 7832, 10761, ...
PROG
(PARI) a(n, k, m=2) = if(n*k<=1, k^n, if(k==1, m*sum(j=1, n-1, a(j, 1)*a(n-j, j)), sum(j=1, n, ((k+1)*j-n)*a(j, 1)*a(n-j, k))/n));
CROSSREFS
KEYWORD
nonn,tabl
AUTHOR
Seiichi Manyama, Apr 06 2026
STATUS
approved
