login

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

A165748
a(n) = (8/9)*(2+7*(-8)^(n-1)).
2
1, 8, -48, 400, -3184, 25488, -203888, 1631120, -13048944, 104391568, -835132528, 6681060240, -53448481904, 427587855248, -3420702841968, 27365622735760, -218924981886064, 1751399855088528, -14011198840708208
OFFSET
0,2
FORMULA
a(n) = (-8)*a(n-1) + 16 for n>=1, with a(0) = 1.
a(n) = 8*a(n-2) - 7*a(n-1), a(0)=1, a(1)=8.
G.f.: (1+15x)/(1+7x-8x^2).
a(n) = Sum_{0<=k<=n} A112555(n,k)*7^(n-k).
From G. C. Greubel, Apr 07 2016: (Start)
a(n) = -7*a(n-1) + 8*a(n-2).
E.g.f.: (1/9)*(16*exp(x) - 7*exp(-8*x)). (End)
MATHEMATICA
Table[(8/9)*(2 + 7*(-8)^(n - 1)), {n, 0, 100}] or
LinearRecurrence[{-7, 8}, {1, 8}, 100] (* G. C. Greubel, Apr 07 2016 *)
PROG
(PARI) x='x+O('x^99); Vec((1+15*x)/(1+7*x-8*x^2)) \\ Altug Alkan, Apr 07 2016
CROSSREFS
Sequence in context: A165049 A013186 A165506 * A220174 A239888 A072169
KEYWORD
easy,sign
AUTHOR
Philippe Deléham, Sep 26 2009
STATUS
approved