| 1, 0, 12, 9, 30, 0, 56, 60, 126, 0, 132, 126, 182, 0, 420, 316, 306, 0, 380, 330, 798, 0, 552, 888, 875, 0, 1296, 630, 870, 0, 992, 1536, 1914, 0, 2100, 1467, 1406, 0, 2652, 2360, 1722, 0, 1892, 1518, 4860, 0, 2256, 4872, 3234, 0, 4488, 2106, 2862, 0, 5060
(list; graph; listen)
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OFFSET
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1,3
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FORMULA
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a(4n+2) = 0.
a(2n+1) = A034715(2n+1), where A034715 is the Dirichlet convolution of triangular numbers with themselves.
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PROGRAM
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(PARI) {a(n) = if( n<1, 0, polcoeff( sum(k=1, n, k*(k+1)/2 * x^k / (1 - (-x)^k)^3, x*O(x^n)), n))}
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CROSSREFS
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Cf. A143520 (variant), A034715.
Sequence in context: A101501 A018870 A068614 this_sequence A038335 A040023 A109683
Adjacent sequences: A163917 A163918 A163919 this_sequence A163921 A163922 A163923
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KEYWORD
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nonn
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AUTHOR
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Paul D. Hanna (pauldhanna(AT)juno.com), Aug 06 2009
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