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A090413
A Chebyshev transform of 3^n.
0
1, 3, 8, 21, 56, 150, 400, 1065, 2840, 7578, 20208, 53874, 143664, 383148, 1021728, 2724465, 7265240, 19374450, 51665200, 137772246, 367392656, 979719348, 2612584928, 6966873546, 18578329456, 49542281220, 132112749920
OFFSET
0,2
FORMULA
G.f.: c(-x^2)/(1-3xc(-x^2)), c(x) g.f. of Catalan numbers A000108; a(n)=sum{k=0..n, (k+1)C(n, n/2-k/2)(-1)^(n/2-k/2)(1+(-1)^(n+k))3^k/(n+k+2)}.
Conjecture: 3*(n+1)*a(n) -8*(n+1)*a(n-1) +12*(n-2)*a(n-2) +32*(2-n)*a(n-3)=0. - R. J. Mathar, Sep 27 2012
CROSSREFS
Sequence in context: A309226 A278616 A278615 * A128105 A085560 A318900
KEYWORD
easy,nonn
AUTHOR
Paul Barry, Dec 05 2003
STATUS
approved