A133669 a(n) = a(n-1) - 49*a(n-2), a(0)=1, a(1)=7.

1, 7, -42, -385, 1673, 20538, -61439, -1067801, 1942710, 54264959, -40927831, -2699910822, -694447103, 131601183175, 165629091222, -6282828884353, -14398654354231, 293459960979066, 998994024336385, -13380544063637849, -62331251256120714

Offset

0,2

Links

Table of n, a(n) for n=0..20.

Index entries for linear recurrences with constant coefficients, signature (1, -49).

Formula

G.f.: (1+6*x)/(1-x+49*x^2) .

a(n) = Sum_{k=0..n} A133607(n,k)*7^k. - Philippe Deléham, Dec 30 2007

Mathematica

LinearRecurrence[{1, -49}, {1, 7}, 20] (* or *)  CoefficientList[ Series[ (1+6x)/(1-x+49x^2), {x, 0, 20}], x] (* Harvey P. Dale, Sep 08 2018 *)

Crossrefs

Cf. A133607.

Sequence in context: A209071 A174224 A278571 * A205340 A304953 A293850

Adjacent sequences: A133666 A133667 A133668 * A133670 A133671 A133672

Keyword

easy,sign

Author

Philippe Deléham, Dec 28 2007

Extensions

More terms from Harvey P. Dale, Sep 08 2018

Status

approved