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A080238 Largest squarefree number dividing sum of cubes of divisors of n. 1
1, 3, 14, 73, 42, 42, 86, 195, 757, 42, 222, 1022, 2198, 258, 42, 4681, 546, 2271, 70, 3066, 602, 222, 78, 2730, 15751, 6594, 5110, 6278, 8130, 42, 266, 4161, 1554, 546, 1806, 55261, 50654, 210, 2198, 2730, 22974, 1806, 39754, 16206, 31794, 78, 4326 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Amiram Eldar, Table of n, a(n) for n = 1..10000

FORMULA

a(n) = A007947(A001158(n)).

EXAMPLE

n=12: sigma_3(12) = 1 + 8 + 27 + 64 + 216 + 1728 = 2044, sqf-kernel = 1022 = 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[3, w]], {w, 1, 100}]

CROSSREFS

Cf. A000213, A001157, A007947.

Sequence in context: A118650 A180187 A295104 * A307443 A213228 A306455

Adjacent sequences:  A080235 A080236 A080237 * A080239 A080240 A080241

KEYWORD

nonn

AUTHOR

Labos Elemer, Mar 19 2003

STATUS

approved

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Last modified December 10 18:10 EST 2019. Contains 329901 sequences. (Running on oeis4.)