id:A132211 - OEIS Search Results

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Coefficients of a Ramanujan q-series.

+0
2

1, -1, 0, 0, 0, 0, -1, 1, -1, 1, -1, 2, -2, 2, -2, 2, -2, 2, -2, 2, -2, 2, -1, 1, -1, 0, 1, -1, 1, -2, 3, -4, 4, -5, 7, -8, 8, -9, 11, -12, 12, -13, 15, -16, 16, -17, 19, -20, 19, -20, 22, -22, 21, -21, 22, -22, 20, -19, 20, -19, 16, -14, 14, -12, 8, -5, 3, 0, -5, 10, -13, 17, -24, 30, -34, 40, -48, 55, -61, 68, -77, 86, -93, 101 (list; graph; listen)

	OFFSET	`0,12`
	FORMULA	`G.f.: Sum_{k>=0} (-1)^k* q^(k*(k+1)/2)/ (q^2;q^2)_n.`
	EXAMPLE	`1 - q - q^6 + q^7 - q^8 + q^9 - q^10 + 2q^11 - 2q^12 + 2*q^13 - ...`
	PROGRAM	`(PARI) {a(n)= local(t); if(n<0, 0, t= 1 +xO(x^n); polcoeff( sum(k=1, (sqrtint(8n+1)-1)\2, t= -t* x^k/ (1-x^(2k)) +xO(x^n), 1), n))}`
	CROSSREFS	`Adjacent sequences: A132208 A132209 A132210 this_sequence A132212 A132213 A132214` `Sequence in context: A098378 A035931 A140438 this_sequence A067441 A044926 A074264`
	KEYWORD	`sign`
	AUTHOR	`Michael Somos, Aug 13 2007`

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Last modified October 13 09:05 EDT 2008. Contains 145008 sequences.

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