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A087787
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Sum_{k=0..n} (-1)^(n-k)*A000041(k).
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5
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1, 0, 2, 1, 4, 3, 8, 7, 15, 15, 27, 29, 48, 53, 82, 94, 137, 160, 225, 265, 362, 430, 572, 683, 892, 1066, 1370, 1640, 2078, 2487, 3117, 3725, 4624, 5519, 6791, 8092, 9885, 11752, 14263, 16922, 20416, 24167, 29007, 34254, 40921, 48213, 57345, 67409
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,3
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COMMENTS
| Essentially first differences of A024786 (see the formula). Also, a(n) is the number of 2's in the outer shell of the partitions of n+2 (see A135010). [From Omar E. Pol (info(AT)polprimos.com), Sep 10 2008]
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FORMULA
| G.f.: 1/(1+x)*1/Product_{k>0} (1-x^k). a(n) = 1/n*Sum_{k=1..n} (sigma(k)+(-1)^k)*a(n-k).
a(n) = A024786(n+2)-A024786(n+1). [From Omar E. Pol (info(AT)polprimos.com), Sep 10 2008]
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CROSSREFS
| Cf. A024786, A135010, A138121, A141285. [From Omar E. Pol (info(AT)polprimos.com), Sep 10 2008]
Sequence in context: A076077 A152194 * A182712 A100818 A005291 A106624
Adjacent sequences: A087784 A087785 A087786 * A087788 A087789 A087790
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KEYWORD
| nonn
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AUTHOR
| Vladeta Jovovic (vladeta(AT)eunet.rs), Oct 07 2003
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