id:A086227 - OEIS Search Results

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a(n)=1/(4i)*sum( i^k*tan(k*Pi/4/n)) where 1<=k<=n and (k,n)=1.

+0
3

-1, 2, -2, 2, -4, 4, -4, 6, -4, 6, -8, 6, -8, 8, -8, 8, -12, 10, -8, 16, -12, 12, -16, 10, -12, 18, -16, 14, -16, 16, -16, 24, -16, 16, -24, 18, -20, 24, -16, 20, -32, 22, -24, 24, -24, 24, -32, 28, -20, 32, -24, 26, -36, 24, -32, 40, -28, 30, -32, 30, -32, 48, -32, 24, -48, 34, -32, 48, -32, 36, -48, 36, -36, 40, -40, 48, -48 (list; graph; listen)

	OFFSET	`2,2`
	PROGRAM	`(PARI) a(n)=round(real(1/4/Isum(k=1, 4n, (I^k)tan(Pi/4/nif(gcd(k, n)-1, 0, k)))))`
	CROSSREFS	`Sequence in context: A007614 A113402 A054861 this_sequence A079438 A123050 A113694` `Adjacent sequences: A086224 A086225 A086226 this_sequence A086228 A086229 A086230`
	KEYWORD	`sign`
	AUTHOR	`Benoit Cloitre (benoit7848c(AT)orange.fr), Aug 28 2003`

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Last modified November 21 14:49 EST 2008. Contains 150807 sequences.

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