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A015056
q-Catalan numbers (binomial version) for q=-2.
0
1, 1, 5, 77, 5117, 1291677, 1333581405, 5441592632541, 89331571319228381, 5848755670855706968541, 1533967407742898704050818525, 1608089383785066648192844419233245
OFFSET
0,3
LINKS
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
KEYWORD
nonn,easy
STATUS
approved