

A138269


a(n+1) is the Hankel transform of C(n)+C(n+2), where C(n)=A000108(n).


0



1, 3, 12, 53, 231, 1000, 4329, 18747, 81188, 351597, 1522639, 6594000, 28556241, 123666803, 535556412, 2319302053, 10044062391, 43497219000, 188370799289, 815766130347, 3532789487188, 15299239691997
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OFFSET

0,2


LINKS

Table of n, a(n) for n=0..21.
Index to sequences with linear recurrences with constant coefficients, signature (5,4,5,1).


FORMULA

G.f.: (1x)^2/(15x+4x^25x^3+x^4); a(n)=Re(P(2n,I)*CONJ(P(2n+1,I))) where I=sqrt(1) and P(n,x)=sum{k=0..floor(n/2), C(nk,k)x^k}.


CROSSREFS

Cf. A092886, A138268.
Sequence in context: A007198 A000256 A124202 * A228771 A151198 A151199
Adjacent sequences: A138266 A138267 A138268 * A138270 A138271 A138272


KEYWORD

easy,nonn


AUTHOR

Paul Barry, Mar 10 2008


STATUS

approved



