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A165638
a(n)=(6/7)*(2+5*(-6)^(n-1)).
1
1, 6, -24, 156, -924, 5556, -33324, 199956, -1199724, 7198356, -43190124, 259140756, -1554844524, 9329067156, -55974402924, 335846417556, -2015078505324, 12090471031956, -72542826191724, 435256957150356
OFFSET
0,2
FORMULA
a(n)=(-6)*a(n-1)+12 with a(0)=1. a(0)=1, a(1)=6, a(n)=6*a(n-2)-5*a(n-1). G.f.: (1+11x)/(1+5x-6x^2). a(n)= Sum_{k, 0<=k<=n} A112555(n,k)*5^(n-k).
MATHEMATICA
LinearRecurrence[{-5, 6}, {1, 6}, 20] (* Harvey P. Dale, Jan 07 2016 *)
CROSSREFS
Sequence in context: A265883 A330498 A165491 * A122829 A232688 A221980
KEYWORD
sign
AUTHOR
Philippe Deléham, Sep 23 2009
STATUS
approved