A165639 a(n)=(7/4)*(1+3*(-7)^(n-1)).

1, 7, -35, 259, -1799, 12607, -88235, 617659, -4323599, 30265207, -211856435, 1482995059, -10380965399, 72666757807, -508667304635, 3560671132459, -24924697927199, 174472885490407, -1221310198432835, 8549171389029859

Offset

0,2

Links

Table of n, a(n) for n=0..19.

Index entries for linear recurrences with constant coefficients, signature (-6,7).

Formula

a(n)=(-7)*a(n-1)+14 with a(0)=1. a(0)=1, a(1)=7, a(n)=7*a(n-2)-6*a(n-1). G.f.: (1+13x)/(1+6x-7x^2). a(n)= Sum_{k, 0<=k<=n} A112555(n,k)*6^(n-k).

a(n) = (-3*(-7)^n + 7)/4. - Charles R Greathouse IV, Jun 05 2026

Mathematica

LinearRecurrence[{-6, 7}, {1, 7}, 30] (* Harvey P. Dale, Jun 05 2016 *)

Prog

(PARI) a(n)=(-3*(-7)^n+7)/4 \\ Charles R Greathouse IV, Jun 05 2026

Crossrefs

Cf. A112555.

Sequence in context: A382473 A096686 A165505 * A073109 A389355 A231511

Adjacent sequences: A165636 A165637 A165638 * A165640 A165641 A165642

Keyword

sign,easy,changed

Author

Philippe Deléham, Sep 23 2009

Status

approved