A074557 3^n + 6^n + 9^n.

3, 18, 126, 972, 7938, 67068, 578826, 5065092, 44732898, 397517868, 3547309626, 31744033812, 284606850258, 2554928116668, 22955161402026, 206361331428132, 1855841341806018, 16694108488251468, 150196195641088026

Offset

0,1

Links

Vincenzo Librandi, Table of n, a(n) for n = 0..1000

Index entries for linear recurrences with constant coefficients, signature (18,-99,162).

Formula

G.f.: 1/(1-3*x)+1/(1-6*x)+1/(1-9*x). E.g.f.: exp(3*x)+exp(6*x)+exp(9*x). [From Mohammad K. Azarian, Dec 30 2008]

Mathematica

Table[3^n + 6^n + 9^n, {n, 0, 20}]

Prog

(Magma) [3^n + 6^n + 9^n: n in [0..20]]; // Vincenzo Librandi, Aug 24 2011

Crossrefs

Cf. A001550, A001576, A034513, A001579, A074501 - A074580.

Sequence in context: A004987 A340894 A363560 * A073971 A366666 A369940

Adjacent sequences: A074554 A074555 A074556 * A074558 A074559 A074560

Keyword

easy,nonn

Author

Robert G. Wilson v, Aug 23 2002

Status

approved