id:A072614 - OEIS Search Results

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Sum( k = 1..n, (-1)^( n reduced mod k) ).

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1, 2, 1, 2, 1, 4, -1, 4, 1, 4, -1, 6, -3, 8, -1, 4, -1, 8, -5, 10, -3, 8, -5, 10, -5, 10, -3, 8, -5, 14, -11, 14, -7, 12, -5, 12, -9, 14, -7, 12, -9, 18, -15, 20, -9, 14, -11, 16, -11, 18, -11, 16, -13, 22, -15, 20, -13, 18, -15, 24, -21, 26, -15, 18, -11, 20, -17, 22, -15, 24, -21, 28, -25, 30, -19, 24, -17, 26, -23, 28, -19, 24 (list; graph; listen)

	OFFSET	`1,2`
	FORMULA	`lim n -> infinity abs(a(n))/n = C = 0.30684(3)....`
	MATHEMATICA	`Table[ Sum[(-1)^ Mod[n, k], {k, 1, n}], {n, 1, 81} ]`
	PROGRAM	`(PARI) a(n)=sum(k=1, n, (-1)^(n%k))`
	CROSSREFS	`Sequence in context: A067005 A135517 A164799 this_sequence A067044 A055684 A024559` `Adjacent sequences: A072611 A072612 A072613 this_sequence A072615 A072616 A072617`
	KEYWORD	`sign`
	AUTHOR	`Benoit Cloitre (benoit7848c(AT)orange.fr), Aug 10 2002`

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Last modified November 24 23:16 EST 2009. Contains 167481 sequences.

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