OFFSET
0,8
LINKS
Paolo Xausa, Table of n, a(n) for n = 0..11324 (first 150 antidiagonals, flattened).
FORMULA
A(0,k) = 1 and A(n,k) = k*(k+2) * A(n-1,k+4) - k*(k+1) * A(n-1,k+2) for n > 0.
EXAMPLE
Square array begins:
1, 1, 1, 1, 1, 1, ...
0, 1, 2, 3, 4, 5, ...
0, 9, 24, 45, 72, 105, ...
0, 225, 720, 1575, 2880, 4725, ...
0, 11025, 40320, 99225, 201600, 363825, ...
0, 893025, 3628800, 9823275, 21772800, 42567525, ...
MATHEMATICA
PROG
(PARI) a(n, k) = if(n==0, 1, k*(k+2)*a(n-1, k+4)-k*(k+1)*a(n-1, k+2));
CROSSREFS
KEYWORD
nonn,tabl
AUTHOR
Seiichi Manyama, Apr 14 2026
STATUS
approved
