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A098131
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Number of compositions of n where the smallest part is greater than or equal to the number of parts.
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0
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1, 1, 1, 2, 3, 4, 5, 6, 8, 11, 15, 20, 26, 33, 41, 51, 64, 81, 103, 131, 166, 209, 261, 323, 397, 486, 594, 726, 888, 1087, 1331, 1629, 1991, 2428, 2952, 3577, 4320, 5202, 6249, 7493, 8973, 10736, 12838, 15345, 18334, 21894, 26127, 31149, 37092, 44107, 52368
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,4
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FORMULA
| G.f.: Sum(x^(k^2)/(1-x)^k, k=0..infinity).
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EXAMPLE
| a(7)=5 because we have 7, 4+3, 3+4, 5+2 and 2+5.
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MAPLE
| G:=sum(x^(k^2)/(1-x)^k, k=0..20):Gser:=series(G, x=0, 56):seq(coeff(Gser, x^n), n=1..54); (Deutsch)
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CROSSREFS
| Cf. A003114, A077229.
Sequence in context: A124067 A060967 A026483 * A017899 A003520 A101915
Adjacent sequences: A098128 A098129 A098130 * A098132 A098133 A098134
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KEYWORD
| easy,nonn
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AUTHOR
| Vladeta Jovovic (vladeta(AT)eunet.rs), Sep 27 2004
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EXTENSIONS
| More terms from Emeric Deutsch (deutsch(AT)duke.poly.edu), Mar 29 2005
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