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A166153
a(n) = (7^n+14*(-8)^n)/15.
3
1, -7, 63, -455, 3983, -29463, 252511, -1902439, 16043055, -122579639, 1020990719, -7885450503, 65060930767, -506646158935, 4150058281887, -32522243182247, 264925506967919, -2086171125173751, 16921999515377215
OFFSET
0,2
FORMULA
a(n) = 56*a(n-2)-a(n-1), a(0)= 1, a(1)= -7, for n>1.
G.f.: (1-6*x)/(1+x-56*x^2).
a(n) = Sum_{k=0..n} A112555(n,k)*(-8)^k.
E.g.f.: (1/15)*(exp(7*x) + 14*exp(-8*x)). - G. C. Greubel, May 01 2016
MATHEMATICA
LinearRecurrence[{-1, 56}, {1, -7}, 50] (* G. C. Greubel, May 01 2016 *)
CROSSREFS
KEYWORD
easy,sign
AUTHOR
Philippe Deléham, Oct 08 2009
STATUS
approved