id:A080398 - OEIS Search Results

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Largest square-free number dividing sum of divisors of n.

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1, 3, 2, 7, 6, 6, 2, 15, 13, 6, 6, 14, 14, 6, 6, 31, 6, 39, 10, 42, 2, 6, 6, 30, 31, 42, 10, 14, 30, 6, 2, 21, 6, 6, 6, 91, 38, 30, 14, 30, 42, 6, 22, 42, 78, 6, 6, 62, 57, 93, 6, 14, 6, 30, 6, 30, 10, 30, 30, 42, 62, 6, 26, 127, 42, 6, 34, 42, 6, 6, 6, 195, 74, 114, 62, 70, 6, 42, 10 (list; graph; listen)

	OFFSET	`1,2`
	FORMULA	`a(n)=A007947[A000213(n)]`
	EXAMPLE	`n=12:sigma[12]=1+2+3+4+6+12=28, sqf-kernel=14=a(12)`
	MATHEMATICA	`ffi[x_] := Flatten[FactorInteger[x]] lf[x_] := Length[FactorInteger[x]] ba[x_] := Table[Part[ffi[x], 2*w-1], {w, 1, lf[x]}] cor[x_] := Apply[Times, ba[x]] Table[cor[DivisorSigma[1, w]], {w, 1, 100}]`
	CROSSREFS	`Cf. A000213, A007947.` `Sequence in context: A126316 A101224 A139285 this_sequence A082321 A057502 A071656` `Adjacent sequences: A080395 A080396 A080397 this_sequence A080399 A080400 A080401`
	KEYWORD	`nonn`
	AUTHOR	`Labos E. (labos(AT)ana.sote.hu), Mar 19 2003`

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Last modified December 18 21:37 EST 2009. Contains 171024 sequences.

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