OFFSET
0,2
LINKS
Michel Marcus, Table of n, a(n) for n = 0..1000
Ömür Deveci and Anthony G. Shannon, Some aspects of Neyman triangles and Delannoy arrays, Mathematica Montisnigri, Volume L, 2021.
FORMULA
a(n) = Sum_{k=0..floor(n/2)} A104684(n-k, k).
G.f.: 1/sqrt(x^4-2*x^2-4*x+1). - Alois P. Heinz, Nov 26 2021
MATHEMATICA
nterms=30; Table[Sum[Binomial[r=n-k, k]Binomial[2r-k, r], {k, 0, Floor[n/2]}], {n, 0, nterms-1}] (* Paolo Xausa, Nov 26 2021 *)
PROG
(PARI) T(n, k) = binomial(n, k)*binomial(2*n-k, n); \\ A104684
a(n) = sum(k=0, n\2, T(n-k, k));
CROSSREFS
KEYWORD
nonn
AUTHOR
Michel Marcus, Nov 26 2021
STATUS
approved