id:A082072 - OEIS Search Results

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A082072

Least common prime-divisor of Sigma[1,n]=A000203(n) and Sigma[2,n]=A001157(n); a(n)=1 if no common prime-divisor was found.

+0
6

1, 1, 2, 7, 2, 2, 2, 5, 13, 2, 2, 2, 2, 2, 2, 31, 2, 13, 2, 2, 2, 2, 2, 2, 31, 2, 2, 2, 2, 2, 2, 3, 2, 2, 2, 7, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 127, 2, 2, 2, 2, 2, 2, 2, 5, 2, 2, 2, 2, 2, 2, 2, 2, 11, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 2, 7, 2, 2 (list; graph; listen)

	OFFSET	`1,3`
	MATHEMATICA	`ffi[x_] := Flatten[FactorInteger[x]] lf[x_] := Length[FactorInteger[x]] ba[x_] := Table[Part[ffi[x], 2*w-1], {w, 1, lf[x]}] f1[x_] := DivisorSigma[1, x]; f2[x_] := DivisorSigma[2, x] Table[Min[Intersection[ba[f1[w]], ba[f2[w]]]], {w, 1, 128}]`
	CROSSREFS	`Cf. A000203, A001157, A082061-A082072.` `Sequence in context: A102886 A072981 A023399 this_sequence A082066 A130335 A073246` `Adjacent sequences: A082069 A082070 A082071 this_sequence A082073 A082074 A082075`
	KEYWORD	`nonn`
	AUTHOR	`Labos E. (labos(AT)ana.sote.hu), Apr 07 2003`

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

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