id:A109413 - OEIS Search Results

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a(n) equals the (n*(n+1)/2)-th partial sum of the self-convolution of A010054, which has the g.f.: Sum_{n>=0} x^(n*(n+1)/2).

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1, 3, 6, 11, 17, 24, 35, 45, 58, 71, 87, 106, 123, 144, 164, 189, 216, 240, 269, 298, 329, 365, 396, 437, 471, 510, 551, 591, 642, 683, 730, 778, 827, 882, 932, 987, 1048, 1105, 1165, 1220, 1289, 1355, 1418, 1485, 1549, 1626, 1699, 1772, 1846, 1923, 2002, 2080 (list; graph; listen)

	OFFSET	`0,2`
	FORMULA	`a(n) = [x^(n(n+1)/2)] [Sum_{k>=0} x^(k(k+1)/2)]^2/(1-x).`
	PROGRAM	`(PARI) {a(n)=local(X=x+xO(x^(n(n+1)/2))); polcoeff((eta(X^2)^2/eta(X))^2/(1-X), n*(n+1)/2)}`
	CROSSREFS	`Cf. A109414, A109415, A010054.` `Adjacent sequences: A109410 A109411 A109412 this_sequence A109414 A109415 A109416` `Sequence in context: A071619 A025735 A023601 this_sequence A003022 A025722 A022775`
	KEYWORD	`nonn`
	AUTHOR	`Paul D. Hanna (pauldhanna(AT)juno.com), Jun 27 2005`

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Last modified October 13 20:18 EDT 2008. Contains 145016 sequences.

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