A136366 - OEIS

%I #17 Jun 06 2021 15:55:37

%S 3,4,5,10,21,31,55,77,121,135,148,192,425,570,612,649,1293,2326,3646

%N Numbers k such that A024530(k) is prime.

%t f=0; Do[ p=Prime[n]; f=f + (-1)^(n+1)*1/p; g=Numerator[f] ;If[ PrimeQ[g], Print[ {n, g} ] ], {n, 1, 150} ]

%Y Cf. A024530 (numerator of Sum_{k=1..n} (-1)^k / prime(k)).

%Y Cf. A136365, A136367, A136368, A136369, A136370, A136371.

%K nonn,more

%O 1,1

%A _Alexander Adamchuk_, Dec 27 2007

%E a(12)-a(16) from _Alexander Adamchuk_, Sep 15 2010

%E a(17)-a(19) from _Robert Price_, Aug 27 2019