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Search: id:A103419
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| A103419 |
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Number of compositions of n in which the least part is odd. |
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+0
4
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| 1, 1, 4, 6, 14, 28, 59, 117, 239, 484, 980, 1973, 3973, 7989, 16054, 32227, 64653, 129628, 259787, 520440, 1042305, 2086938, 4177680, 8361557, 16733221, 33482909, 66992641, 134028938, 268128902, 536373288, 1072934271, 2146173471
(list; graph; listen)
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OFFSET
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1,3
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FORMULA
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G.f.: Sum((1-x)^2*x^(2*n-1)/((1-x-x^(2*n))*(1-x-x^(2*n-1))), n=1..infinity).
G.f.: Sum(x^k/((1-x)^k*(1+x^k)),k=1..infinity). - Vladeta Jovovic (vladeta(AT)Eunet.yu), Mar 02 2008
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MATHEMATICA
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Rest[ CoefficientList[ Series[ Expand[ Sum[(1 - x)^2*x^(2n - 1)/((1 - x - x^(2n))*(1 - x - x^(2n - 1))), {n, 35}]], {x, 0, 35}], x]] (from Robert G. Wilson v Feb 05 2005)
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CROSSREFS
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Cf. A103420-A103422, A027187, A027193, A026804, A026805.
Sequence in context: A084214 A030138 A009849 this_sequence A005202 A106526 A108516
Adjacent sequences: A103416 A103417 A103418 this_sequence A103420 A103421 A103422
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KEYWORD
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easy,nonn
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AUTHOR
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Vladeta Jovovic (vladeta(AT)Eunet.yu), Feb 04 2005
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EXTENSIONS
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More terms from Robert G. Wilson v (rgwv(AT)rgwv.com), Feb 05 2005
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