A015056 q-Catalan numbers (binomial version) for q=-2.

1, 1, 5, 77, 5117, 1291677, 1333581405, 5441592632541, 89331571319228381, 5848755670855706968541, 1533967407742898704050818525, 1608089383785066648192844419233245

Offset

0,3

Links

Table of n, a(n) for n=0..11.

Paul Barry, On Integer-Sequence-Based Constructions of Generalized Pascal Triangles, Journal of Integer Sequences, Vol. 9 (2006), Article 06.2.4.

Formula

a(n) = {1 / (n+1)_q} {2 n choose n}_q.

Mathematica

Table[3 QBinomial[2n, n, -2]/(1 - (-2)^(n+1)), {n, 0, 20}] (* Vladimir Reshetnikov, Sep 16 2016 *)

Crossrefs

Sequence in context: A318236 A009485 A188455 * A326870 A327903 A214443

Adjacent sequences: A015053 A015054 A015055 * A015057 A015058 A015059

Keyword

nonn,easy

Author

Olivier Gérard

Status

approved