A165230 - OEIS

A165230

a(0)=1, a(1)=7, a(n)=14*a(n-1)-7*a(n-2) for n>1 .

1, 7, 91, 1225, 16513, 222607, 3000907, 40454449, 545355937, 7351801975, 99107736091, 1336045691449, 18010885527649, 242800077546943, 3273124886963659, 44124147874662625, 594826196036531137, 8018697709388797543, 108097984559187447643, 1457240899862902684201

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OFFSET

0,2

LINKS

Harvey P. Dale, Table of n, a(n) for n = 0..885

Index entries for linear recurrences with constant coefficients, signature (14,-7).

FORMULA

G.f.: (1-7*x)/(1-14*x+7*x^2) .

a(n) = (1/2)*((7+sqrt(42))^n+(7-sqrt(42))^n). [Paolo P. Lava, Sep 16 2009]

MATHEMATICA

LinearRecurrence[{14, -7}, {1, 7}, 20] (* Harvey P. Dale, Dec 18 2016 *)

CROSSREFS