id:A091895 - OEIS Search Results

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Least number k such that the denominator of d(k)/k = n, or zero if no such number exist.

+0
3

1, 8, 3, 4, 5, 72, 7, 80, 108, 20, 11, 240, 13, 28, 15, 16, 17, 0, 19, 480, 21, 44, 23, 48, 25, 52, 27, 560, 29, 0, 31, 448, 33, 68, 35, 864, 37, 76, 39, 160, 41, 1680, 43, 880, 540, 92, 47, 144, 49, 200, 51, 1040, 53, 972, 55, 112, 57, 116, 59, 1920, 61, 124, 756, 64, 65 (list; graph; listen)

	OFFSET	`1,2`
	COMMENT	`k is a multiple of n.`
	MATHEMATICA	`a = Table[0, {100}]; Do[b = Denominator[DivisorSigma[0, n]/n]; If[b < 101 && a[[b]] == 0, a[[b]] = n], {n, 1, 2640}]; a`
	CROSSREFS	`Cf. A090395, zeros are in A091896.` `Sequence in context: A021849 A070474 A070597 this_sequence A111436 A014549 A021549` `Adjacent sequences: A091892 A091893 A091894 this_sequence A091896 A091897 A091898`
	KEYWORD	`nonn`
	AUTHOR	`Robert G. Wilson v (rgwv(AT)rgwv.com), Feb 09 2004`

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Last modified December 11 12:57 EST 2009. Contains 170656 sequences.

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