id:A115378 - OEIS Search Results

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a(n) = number of positive integers k < n such that n XOR k = (n+k).

+0
2

0, 1, 0, 3, 1, 1, 0, 7, 3, 3, 1, 3, 1, 1, 0, 15, 7, 7, 3, 7, 3, 3, 1, 7, 3, 3, 1, 3, 1, 1, 0, 31, 15, 15, 7, 15, 7, 7, 3, 15, 7, 7, 3, 7, 3, 3, 1, 15, 7, 7, 3, 7, 3, 3, 1, 7, 3, 3, 1, 3, 1, 1, 0, 63, 31, 31, 15, 31, 15, 15, 7, 31, 15, 15, 7, 15, 7, 7, 3, 31, 15, 15, 7, 15, 7, 7, 3, 15, 7, 7, 3, 7, 3 (list; graph; listen)

	OFFSET	`1,4`
	COMMENT	`The number of positive integers k < n such that n XOR k = (n-k) is A038573(n).`
	FORMULA	`a(n) = -1 + 2^(number of 0's in binary expansion of n). a(n) = 2^A080791(n) - 1 = A080100(n) - 1.`
	PROGRAM	`(PARI) a(n)=sum(k=1, n, if(bitxor(n, k)==(n+k), 1, 0))`
	CROSSREFS	`Cf. A080791, A080100, A038573.` `Sequence in context: A130160 A124801 A124926 this_sequence A120060 A143295 A104608` `Adjacent sequences: A115375 A115376 A115377 this_sequence A115379 A115380 A115381`
	KEYWORD	`nonn`
	AUTHOR	`Paul D. Hanna (pauldhanna(AT)juno.com), Jan 21 2006`

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Last modified November 18 20:14 EST 2008. Contains 147244 sequences.

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