A125708 - OEIS

%I #12 Aug 04 2024 08:56:07

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

%N Numbers k such that A115963(k) is prime.

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

%C a(9) > 5000. - _Michael S. Branicky_, Aug 04 2024

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

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

%K hard,more,nonn

%O 1,1

%A _Alexander Adamchuk_, Feb 01 2007, Mar 01 2007

%E a(6) from _Alexander Adamchuk_, Sep 16 2010

%E a(7)-a(8) from _Amiram Eldar_, Feb 18 2019