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1, 20, 400, 8000, 160000, 3200000, 64000000, 1280000000, 25600000000, 512000000000, 10240000000000, 204800000000000, 4096000000000000, 81920000000000000, 1638400000000000000, 32768000000000000000
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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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 20-colored compositions of n such that no adjacent parts have the same color. - Milan Janjic, Nov 17 2011
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LINKS
| T. D. Noe, Table of n, a(n) for n=0..100
Tanya Khovanova, Recursive Sequences
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FORMULA
| G.f.: 1/(1-20x), e.g.f.: exp(20x)
a(n)=20^n; a(n)=20*a(n-1) n>0 a(0)=1 [From Vincenzo Librandi, Nov 21 2010]
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PROG
| (Other) sage: [lucas_number1(n, 20, 0) for n in xrange(1, 17)]# [From Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Apr 29 2009]
(MAGMA)[20^n: n in [0..100]] [From Vincenzo Librandi, Nov 21 2010]
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CROSSREFS
| a(n) = A159991(n)/A000244(n). [From Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), May 02 2009]
Sequence in context: A057745 A189198 A171294 * A007577 A048987 A006494
Adjacent sequences: A009961 A009962 A009963 * A009965 A009966 A009967
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KEYWORD
| nonn,easy
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
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