id:A143277 - OEIS Search Results

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G.f.: Product_{k>0} (1 - x^(3*k))^2 / (1 - x^(3*k - 2)).

+0
1

1, 1, 1, -1, 0, 0, -1, -2, -1, 1, -1, -2, 0, 0, -1, 0, 2, 1, -2, 0, 1, 1, 1, 2, 0, 1, 1, -1, -1, 2, 3, -1, 0, 2, -1, -1, 1, 1, -3, 0, 0, -1, 1, 2, 0, -3, -1, -2, -2, 1, 0, -1, 0, 0, -2, 0, 2, -2, -1, 0, -2, -2, 1, 1, -1, 2, 0, -2, 1, 2, -1, 0, 3, -2, -1, 2, -1, -3, 3, 2, -1, 3, 5, -1, -2, 1, 0, 0, 1, -1, 0, 2, 0, 0, 3, 1, -2, 0, 0, 0, 4, 2, -3, 1, 1 (list; graph; listen)

	OFFSET	`0,8`
	FORMULA	`Euler transform of period 3 sequence [ 1, 0, -2, ...].`
	EXAMPLE	`1 + q + q^2 - q^3 - q^6 - 2q^7 - q^8 + q^9 - q^10 - 2q^11 - q^14 + ...`
	PROGRAM	`(PARI) {a(n) = if( n<0, 0, polcoeff( prod(k=1, n, (1 - x^k)^([2, -1, 0][k%3 + 1]), 1 + x * O(x^n)), n))}`
	CROSSREFS	`Sequence in context: A134744 A016541 A098876 this_sequence A056563 A088231 A143262` `Adjacent sequences: A143274 A143275 A143276 this_sequence A143278 A143279 A143280`
	KEYWORD	`sign`
	AUTHOR	`Michael Somos, Aug 04 2008`

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Last modified November 25 20:09 EST 2009. Contains 167514 sequences.

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