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A074610 a(n) = 3^n + 9^n. 1
2, 12, 90, 756, 6642, 59292, 532170, 4785156, 43053282, 387440172, 3486843450, 31381236756, 282430067922, 2541867422652, 22876797237930, 205891146443556, 1853020231898562, 16677181828806732, 150094635684419610 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

LINKS

Table of n, a(n) for n=0..18.

Index entries for linear recurrences with constant coefficients, signature (12,-27).

FORMULA

From Mohammad K. Azarian, Jan 11 2009: (Start)

G.f.: 1/(1-3*x) + 1/(1-9*x).

E.g.f.: e^(3*x) + e^(9*x). (End)

a(n) = 12*a(n-1) - 27*a(n-2) with a(0)=2, a(1)=12. - Vincenzo Librandi, Jul 21 2010

MATHEMATICA

Table[3^n + 9^n, {n, 0, 25}]

CROSSREFS

Cf. A000051, A034472, A052539, A034474, A062394, A034491, A062395, A062396, A007689, A063376, A063481, A074600..A074624.

Sequence in context: A174356 A121357 A098926 * A250130 A225573 A155639

Adjacent sequences:  A074607 A074608 A074609 * A074611 A074612 A074613

KEYWORD

easy,nonn

AUTHOR

Robert G. Wilson v, Aug 25 2002

STATUS

approved

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Last modified April 19 06:30 EDT 2019. Contains 322237 sequences. (Running on oeis4.)