A215140 - OEIS

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

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OFFSET

1,3

LINKS

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

EXAMPLE

1.127282017283265890344379...

MATHEMATICA

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

PROG

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

CROSSREFS