OFFSET
1,2
EXAMPLE
n=43:sigma[43]=44;
MATHEMATICA
rd[x_] := Length[Union[IntegerDigits[x]]] Do[s = rd[DivisorSigma[1, n]]; s1 = DivisorSigma[1, n]; If[Equal[s, 1], Print[{n, s1}]; ta[[u]] = n; u = u + 1], {n, 1, 1000000}]; ta; DivisorSigma[1, ta]
CROSSREFS
KEYWORD
base,nonn
AUTHOR
Labos Elemer, Jul 15 2004
STATUS
approved