id:A080402 - OEIS Search Results

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A001157(n) is not square-free: sum of squares of divisors of n is not square-free.

+0
2

6, 7, 14, 15, 21, 24, 26, 27, 28, 30, 33, 34, 35, 36, 39, 41, 42, 43, 45, 46, 51, 54, 55, 56, 57, 60, 63, 65, 66, 69, 70, 74, 77, 78, 81, 82, 84, 85, 86, 87, 90, 91, 93, 94, 95, 96, 100, 102, 104, 105, 106, 107, 108, 110, 111, 112, 114, 115, 119, 120, 123, 125, 126, 129 (list; graph; listen)

	OFFSET	`1,1`
	FORMULA	`mu[sigma[2, a(n)]]=0.`
	MATHEMATICA	`Do[s=MoebiusMu[DivisorSigma[2, n]]; If[Equal[s, 0], Print[n]], {n, 1, 1000}]`
	CROSSREFS	`Cf. A001157, A065300, A080401.` `Sequence in context: A041999 A041319 A042315 this_sequence A146308 A047589 A125996` `Adjacent sequences: A080399 A080400 A080401 this_sequence A080403 A080404 A080405`
	KEYWORD	`nonn`
	AUTHOR	`Labos E. (labos(AT)ana.sote.hu), Mar 19 2003`

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Last modified November 27 14:50 EST 2009. Contains 167570 sequences.

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