OFFSET
0,18
LINKS
Alois P. Heinz, Antidiagonals n = 0..55, flattened
J. Fürlinger, J. Hofbauer, q-Catalan numbers, Journal of Combinatorial Theory, Series A, Volume 40, Issue 2, November 1985, Pages 248-264.
Robin Sulzgruber, The Symmetry of the q,t-Catalan Numbers, Masterarbeit, University of Vienna. Fakultät für Mathematik, 2013.
FORMULA
G.f. of column k: 1/(1-x/(1+k*x/(1-k^2*x/(1+k^3*x/(1-k^4*x/(1+ ... )))))).
A(n,k) = Sum_{j=0..n-1} A(j,k)*A(n-j-1,k)*(-k)^j for n>0, A(0,k) = 1.
EXAMPLE
Square array A(n,k) begins:
1, 1, 1, 1, 1, 1, ...
1, 1, 1, 1, 1, 1, ...
1, 0, -1, -2, -3, -4, ...
1, -1, -7, -23, -55, -109, ...
1, 0, 47, 586, 3429, 13436, ...
1, 2, 873, 48778, 885137, 8425506, ...
MAPLE
A:= proc(n, k) option remember; `if`(n=0, 1, add(
A(j, k)*A(n-j-1, k)*(-k)^j, j=0..n-1))
end:
seq(seq(A(n, d-n), n=0..d), d=0..12);
MATHEMATICA
Unprotect[Power]; Power[0|0., 0|0.]=1; Protect[Power]; A[n_, k_]:=A[n, k]=If[n==0 , 1, Sum[A[j, k] A[n - j - 1, k]* (-k)^j, {j, 0, n - 1}]]; Table[A[n, d - n], {d, 0, 15}, {n, 0, d}] (* Indranil Ghosh, Aug 13 2017 *)
PROG
(Python)
from sympy.core.cache import cacheit
@cacheit
def A(n, k):
return 1 if n==0 else sum(A(j, k)*A(n - j - 1, k)*(-k)**j for j in range(n))
for d in range(16): print([A(n, d - n) for n in range(d + 1)]) # Indranil Ghosh, Aug 13 2017
CROSSREFS
KEYWORD
sign,tabl
AUTHOR
Alois P. Heinz, Aug 10 2017
STATUS
approved