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Search: id:A140354
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| 1, 20, 220, 1760, 11440, 64064, 320320, 1464320, 6223360, 24893440, 94595072, 343982080, 1203937280, 4074864640, 13388840960, 42844291072, 133888409600, 409541017600, 1228623052800, 3621204787200, 10501493882880, 30004268236800
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OFFSET
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0,2
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COMMENT
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With a different offset, number of n-permutations (n>=9) of 3 objects: u, v, z with repetition allowed, containing exactly nine (9) u's.
If n=9 then a(0)= 1
Example: a(1)=20 because we have
uuuuuuuuuv, uuuuuuuuvu, uuuuuuuvuu, uuuuuuvuuu, uuuuuvuuuu, uuuuvuuuuu, uuuvuuuuuu, uuvuuuuuuu, uvuuuuuuuu, vuuuuuuuuu, uuuuuuuuuz, uuuuuuuuzu, uuuuuuuzuu, uuuuuuzuuu, uuuuuzuuuu, uuuuzuuuuu, uuuzuuuuuu, uuzuuuuuuu, uzuuuuuuuu and zuuuuuuuuu.
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MAPLE
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seq(binomial(n+9, 9)*2^n, n=0..23);
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PROGRAM
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(Other) SAGE: [lucas_number2(n, 2, 0)*binomial(n, 9)/512 for n in xrange(9, 31)] [From Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Mar 10 2009]
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CROSSREFS
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Sequence in context: A125408 A140236 A004411 this_sequence A155673 A000833 A054329
Adjacent sequences: A140351 A140352 A140353 this_sequence A140355 A140356 A140357
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KEYWORD
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nonn
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AUTHOR
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Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Jun 23 2008
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