OFFSET
1,3
FORMULA
a(n)=Min{x; A048250[x]=n}, a(n)=0 if no solutions.
EXAMPLE
n=256: a(256)=217=7.31, all divisors are squarefree and 1+7+31+217=256=n.
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]] t = Table[0, {256}]; Do[s = DivisorSigma[1, cor[n]]; If[s < 257 && t[[s]] == 0, t[[s]] = n], {n, 10^6}]; t
CROSSREFS
KEYWORD
nonn
AUTHOR
Labos Elemer, May 22 2002
EXTENSIONS
Definition corrected by Jaroslav Krizek, May 28 2014
STATUS
approved