id:A080401 - OEIS Search Results

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A001157(n) is square-free: sum of squares of divisors of n is square-free.

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	OFFSET	`1,2`
	FORMULA	`Abs[mu[sigma[2, a(n)]]]=1.`
	MATHEMATICA	`Do[s=MoebiusMu[DivisorSigma[2, n]]; If[ !Equal[s, 0], Print[n]], {n, 1, 1000}]`
	CROSSREFS	`Cf. A001157, A065300.` `Sequence in context: A047602 A039076 A037471 this_sequence A031482 A047369 A004827` `Adjacent sequences: A080398 A080399 A080400 this_sequence A080402 A080403 A080404`
	KEYWORD	`nonn`
	AUTHOR	`Labos E. (labos(AT)ana.sote.hu), Mar 19 2003`

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Last modified November 27 22:38 EST 2009. Contains 167602 sequences.

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