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A096842
Sigma applied to A096841 produces these repdigits: a[n]=A000203[A096841(n)].
0
1, 3, 4, 7, 6, 8, 44, 222, 444, 888, 444, 888, 888, 2222, 6666, 8888, 8888, 222222, 88888, 222222, 444444, 444444, 888888, 444444, 444444, 666666, 888888, 888888, 888888, 888888, 888888, 444444, 444444, 888888, 888888, 888888, 888888, 888888
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