id:A109008 - OEIS Search Results

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GCD(n,4).

+0
4

4, 1, 2, 1, 4, 1, 2, 1, 4, 1, 2, 1, 4, 1, 2, 1, 4, 1, 2, 1, 4, 1, 2, 1, 4, 1, 2, 1, 4, 1, 2, 1, 4, 1, 2, 1, 4, 1, 2, 1, 4, 1, 2, 1, 4, 1, 2, 1, 4, 1, 2, 1, 4, 1, 2, 1, 4, 1, 2, 1, 4, 1, 2, 1, 4, 1, 2, 1, 4, 1, 2, 1, 4, 1, 2, 1, 4, 1, 2, 1, 4, 1, 2, 1, 4, 1, 2, 1, 4, 1, 2, 1, 4, 1, 2, 1, 4, 1, 2, 1, 4 (list; graph; listen)

	OFFSET	`0,1`
	FORMULA	`a(n) = 1 + [2\|n] + 2[4\|n] = 2 + (-1)^n + cos(nPi/2), where [x\|y] = 1 when x divides y, 0 otherwise.` `a(n) = a(n-4).` `Multiplicative with a(p^e, 4) = GCD(p^e, 4). David W. Wilson (davidwwilson(AT)comcast.net) Jun 12, 2005.`
	CROSSREFS	`Cf. A109004.` `Sequence in context: A010640 A087230 A030787 this_sequence A074695 A069098 A126241` `Adjacent sequences: A109005 A109006 A109007 this_sequence A109009 A109010 A109011`
	KEYWORD	`nonn,easy,mult`
	AUTHOR	`Mitch Harris (Harris.Mitchell(AT)mgh.harvard.edu)`

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

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