A215140 Decimal expansion of Sum_{n>=1} 1 / sigma(n)^n.

1, 1, 2, 7, 2, 8, 2, 0, 1, 7, 2, 8, 3, 2, 6, 5, 8, 9, 0, 3, 4, 4, 3, 7, 9, 7, 2, 3, 2, 7, 2, 5, 0, 6, 1, 3, 5, 6, 6, 1, 4, 1, 2, 3, 0, 9, 9, 8, 4, 9, 3, 1, 2, 2, 4, 5, 4, 0, 9, 6, 5, 5, 6, 2, 7, 3, 8, 6, 4, 3, 1, 9, 5, 1, 8, 1, 5, 2, 5, 9, 6, 7, 0, 6, 3, 4, 9

Offset: 1

Author

Michel Lagneau, Aug 04 2012

Keywords

• nonn
• cons

Examples

			1.127282017283265890344379...
		

Links

• G. C. Greubel, Table of n, a(n) for n = 1..5000

Crossrefs

Cf. A000203.

Programs

Mathematica

RealDigits[N[Sum[1/DivisorSigma[1,n]^n,{n,1,105}],105]][[1]]

PARI

suminf(n=1, 1/sigma(n)^n) \\ Michel Marcus, Apr 20 2018