A165622 a(n)=(-4)*a(n-1)+8 with a(0)=1.

1, 4, -8, 40, -152, 616, -2456, 9832, -39320, 157288, -629144, 2516584, -10066328, 40265320, -161061272, 644245096, -2576980376, 10307921512, -41231686040, 164926744168, -659706976664, 2638827906664, -10555311626648, 42221246506600, -168884986026392

Offset: 0

Author

Philippe Deléham, Sep 22 2009

Keywords

• easy
• sign

Comments

lim_{n -> infinity} a(n)/a(n-1) = -4. [From Klaus Brockhaus, Sep 26 2009]

Crossrefs

Cf. A122117,

Programs

Mathematica

NestList[8-4#&,1,30] (* Harvey P. Dale, Jul 11 2015 *)

Formula

G.f.: (1+7x)/(1+3x-4x^2). a(n)= Sum_{k, 0<=k<=n} A112555(n,k)*3^(n-k). a(0)=1, a(1)=4, a(n)=4*a(n-2)-3*a(n-1).

a(n) = (8-3*(-4)^n)/5. [From Klaus Brockhaus and Paolo P. Lava, Sep 26 2009]

Extensions

Corrected and extended by Harvey P. Dale, Jul 11 2015