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Search: id:A104632
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| A104632 |
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1/n times A104631(n), the coefficient of x^(2n+1) in the expansion of (1+x+x^2+x^3+x^4)^n. |
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+0
2
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| 1, 2, 6, 20, 73, 281, 1125, 4635, 19525, 83710, 364070, 1602327, 7123041, 31937010, 144255802, 655804649, 2998354717, 13777825186, 63596593430, 294743653360, 1371017707245, 6398580086645, 29952930770185, 140604572777250
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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This sequence may be viewed as a higher-order form of the Motzkin numbers, A001006, which are 1/n times the coefficient of x^(n+1) in the expansion of (1+x+x^2)^n. According to Superseeker, this sequence is the INVERT transform of A104184, which is related to Motzkin numbers also. See A104631 for additional comments.
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MATHEMATICA
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f=1; Table[f=Expand[f(x^4+x^3+x^2+x+1)]; Coefficient[f, x, 2n+1]/n, {n, 30}]
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CROSSREFS
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Cf. A005717 (coefficient of x^(n+1) in the expansion of (1+x+x^2)^n).
Sequence in context: A059279 A052884 A061396 this_sequence A107284 A006850 A034010
Adjacent sequences: A104629 A104630 A104631 this_sequence A104633 A104634 A104635
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KEYWORD
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easy,nonn
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AUTHOR
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T. D. Noe (noe(AT)sspectra.com), Mar 17 2005
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