A171556 a(n)=3*C(n)-2, where C(n)=A000108(n).

1, 1, 4, 13, 40, 124, 394, 1285, 4288, 14584, 50386, 176356, 624034, 2228698, 8023318, 29084533, 106073008, 388934368, 1432916098, 5301789568, 19692361258, 73398801058, 274447690918, 1029178840948, 3869712441970, 14585839204354

Offset

0,3

Comments

Hankel transform is A171557.

Links

Table of n, a(n) for n=0..25.

Formula

G.f.: 3*(1-sqrt(1-4x))/(2x)-2/(1-x).

Starting with offset 1 = Narayana transform (A001263) of [1,3,3,3,...]. - Gary W. Adamson, Jul 29 2011

Conjecture: (n+1)*(n-2)*a(n) +(-5*n^2+11*n-4)*a(n-1) +2*(n-1)*(2*n-3)*a(n-2)=0. - R. J. Mathar, Sep 30 2012

Crossrefs

Sequence in context: A261547 A091141 A098183 * A227747 A094628 A034742

Adjacent sequences: A171553 A171554 A171555 * A171557 A171558 A171559

Keyword

easy,nonn

Author

Paul Barry, Dec 11 2009

Status

approved