id:A038713 - OEIS Search Results

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a(n) = n XOR (n-1), i.e. nim-sum of sequential pairs, written in binary.

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1, 11, 1, 111, 1, 11, 1, 1111, 1, 11, 1, 111, 1, 11, 1, 11111, 1, 11, 1, 111, 1, 11, 1, 1111, 1, 11, 1, 111, 1, 11, 1, 111111, 1, 11, 1, 111, 1, 11, 1, 1111, 1, 11, 1, 111, 1, 11, 1, 11111, 1, 11, 1, 111, 1, 11, 1, 1111, 1, 11, 1, 111, 1, 11, 1, 1111111, 1, 11, 1, 111, 1 (list; graph; listen)

	OFFSET	`1,2`
	LINKS	`Index entries for sequences related to Nim-sums`
	FORMULA	`a(n) = (10^A001511(n)-1)/(10-1)` `Multiplicative with a(2^e)=(10^(e+1)-1)/9, a(p^e)=1 if p odd.` `Multiplicative with a(p^e) = (10^e-1)/9 if p = 2, 1 otherwise`
	EXAMPLE	`a(6) = 11 because 110 XOR 101 = 11 base 2`
	PROGRAM	`(PARI) a(n)=if(n<1, 0, (10^(valuation(n, 2)+1)-1)/9) /* Michael Somos Apr 28 2005 */`
	CROSSREFS	`Cf. A038712 translated to binary, A001511 translated to unary (repeated 1's)` `Sequence in context: A086994 A104490 A164851 this_sequence A130556 A120449 A101623` `Adjacent sequences: A038710 A038711 A038712 this_sequence A038714 A038715 A038716`
	KEYWORD	`mult,easy,nonn`
	AUTHOR	`Henry Bottomley (se16(AT)btinternet.com), May 02 2000`

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Last modified December 6 13:45 EST 2009. Contains 170429 sequences.

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