id:A109127 - OEIS Search Results

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Expansion of q^(-1/8)*(eta(q^3)-eta(q)^3)/3 in powers of q.

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1, 0, -2, 0, 0, 2, 0, 0, 0, -3, 0, 0, 0, 0, 4, 0, 0, 0, 0, 0, -4, 0, 0, 0, 0, 0, 0, 5, 0, 0, 0, 0, 0, 0, 0, -6, 0, 0, 0, 0, 0, 0, 0, 0, 6, 0, 0, 0, 0, 0, 0, 0, 0, 0, -7, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 8, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -8, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 9, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -10 (list; graph; listen)

	OFFSET	`1,3`
	FORMULA	`G.f.: Sum_{k>1} (-1)^k[(2k)/3]x^((k^2-k)/2).`
	PROGRAM	`(PARI) {a(n)=if(n<0, 0, A=xO(x^n); 1/3polcoeff( eta(x^3+A)-eta(x+A)^3, n))}` `(PARI) {a(n)=if(n<0, 0, if(issquare(8n+1, &n), ((n+1)\3)(-1)^((n+1)/2)))}`
	CROSSREFS	`Adjacent sequences: A109124 A109125 A109126 this_sequence A109128 A109129 A109130` `Sequence in context: A108497 A108498 A130209 this_sequence A002284 A016424 A108913`
	KEYWORD	`sign`
	AUTHOR	`Michael Somos, Jun 19 2005`

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

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