A125708 Numbers k such that A115963(k) is prime.

3, 5, 9, 43, 150, 300, 516, 1254

Offset

1,1

Comments

A115963(n) is the numerator of Sum_{k=1..n} 1/prime(k)^3.

Links

Table of n, a(n) for n=1..8.

Mathematica

f=0; Do[p=Prime[n]; f=f+1/p^3; g=Numerator[f]; If[PrimeQ[g], Print[{n, p, g}]], {n, 1, 50}]

Crossrefs

Cf. A115963, A024451, A092062, A061015, A109628.

Sequence in context: A246666 A027715 A082703 * A055289 A124974 A336144

Adjacent sequences: A125705 A125706 A125707 * A125709 A125710 A125711

Keyword

hard,more,nonn

Author

Alexander Adamchuk, Feb 01 2007, Mar 01 2007

Extensions

a(6) from Alexander Adamchuk, Sep 16 2010

a(7)-a(8) from Amiram Eldar, Feb 18 2019

Status

approved