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A009971 Powers of 27. 26
1, 27, 729, 19683, 531441, 14348907, 387420489, 10460353203, 282429536481, 7625597484987, 205891132094649, 5559060566555523, 150094635296999121, 4052555153018976267, 109418989131512359209, 2954312706550833698643 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

The compositions of n in which each natural number is colored by one of p different colors are called p-colored compositions of n. For n>=1, a(n) equals the number of 27-colored compositions of n such that no adjacent parts have the same color. - Milan Janjic, Nov 17 2011

LINKS

T. D. Noe, Table of n, a(n) for n = 0..100

Tanya Khovanova, Recursive Sequences

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

FORMULA

G.f.: 1/(1-27*x). - Philippe Deléham, Nov 24 2008

a(n)=27^n; a(n)=27*a(n-1) n>0 a(0)=1 [From Vincenzo Librandi, Nov 21 2010]

PROG

(Sage) [lucas_number1(n, 27, 0) for n in xrange(1, 17)]# Zerinvary Lajos, Apr 29 2009

(MAGMA)[27^n: n in [0..100]] /* Vincenzo Librandi, Nov 21 2010

(PARI) a(n)=27^n \\ Charles R Greathouse IV, Sep 24 2015

CROSSREFS

Sequence in context: A171301 A098838 A268015 * A046240 A042406 A279652

Adjacent sequences:  A009968 A009969 A009970 * A009972 A009973 A009974

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane.

STATUS

approved

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Last modified March 26 18:46 EDT 2017. Contains 284137 sequences.