A096842 Sigma applied to A096841 produces these repdigits: a[n]=A000203[A096841(n)].

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

Author

Labos Elemer, Jul 15 2004

Keywords

• base
• nonn

Examples

			n=43:sigma[43]=44;
		

Crossrefs

Cf. A096503-A096508, A096841-A096846, A000203.

Programs

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]