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A165405 a(0)=1, a(1)=3,a(n)=6*a(n-2)-a(n-1). 2
1, 3, 3, 15, 3, 87, -69, 591, -1005, 4551, -10581, 37887, -101373, 328695, -936933, 2909103, -8530701, 25985319, -77169525, 233081439, -696098589, 2094587223, -6271178757, 18838702095, -56465774637, 169497987207, -508292635029 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

a(n)/a(n-1) tends to -3.

LINKS

Table of n, a(n) for n=0..26.

FORMULA

G.f.: (1+4x)/(1+x-6x^2). a(n)= Sum_{k, 0<=k<=n}A112555(n,k)*2^k.

a(n) = (6*2^n-(-3)^n)/5. [From Klaus Brockhaus, Sep 26 2009]

CROSSREFS

Sequence in context: A131943 A100371 A100347 * A179857 A163590 A114320

Adjacent sequences:  A165402 A165403 A165404 * A165406 A165407 A165408

KEYWORD

sign

AUTHOR

Philippe Deléham, Sep 17 2009

STATUS

approved

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Last modified November 24 16:46 EST 2014. Contains 249899 sequences.