id:A140670 - OEIS Search Results

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a(n) is one if n is odd else one less than largest power of two dividing it.

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1, 1, 1, 3, 1, 1, 1, 7, 1, 1, 1, 3, 1, 1, 1, 15, 1, 1, 1, 3, 1, 1, 1, 7, 1, 1, 1, 3, 1, 1, 1, 31, 1, 1, 1, 3, 1, 1, 1, 7, 1, 1, 1, 3, 1, 1, 1, 15, 1, 1, 1, 3, 1, 1, 1, 7, 1, 1, 1, 3, 1, 1, 1, 63, 1, 1, 1, 3, 1, 1, 1, 7, 1, 1, 1, 3, 1, 1, 1, 15, 1, 1, 1, 3, 1, 1, 1, 7, 1, 1, 1, 3, 1, 1, 1, 31, 1, 1, 1, 3, 1, 1 (list; graph; listen)

	OFFSET	`1,4`
	FORMULA	`a(n) is multiplicative with a(2^e) = 2^e - 1 if e>0, a(p^e) = 1 if p>2.` `a(2n + 1) = 1. a(-n) = a(n). a(2n) = 2 * a(n) + (-1)^n unless n=0.`
	PROGRAM	`(PARI) {a(n) = if(n==0, 0, if(n%2, 1, 2^valuation(n, 2) - 1))}`
	CROSSREFS	`Adjacent sequences: A140667 A140668 A140669 this_sequence A140671 A140672 A140673` `Sequence in context: A124372 A126470 A102480 this_sequence A068845 A081297 A110180`
	KEYWORD	`nonn,mult`
	AUTHOR	`Michael Somos, May 21 2008`

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Last modified October 7 14:39 EDT 2008. Contains 144666 sequences.

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