A136371 Numbers k such that A136370(k) is prime.

1, 2, 3, 5, 46, 227, 232, 336, 360, 3919

Offset: 1

Author

Alexander Adamchuk, Dec 27 2007

Keywords

• nonn
• more

Crossrefs

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

Cf. A136368: numerator of Sum_{k=1..n} (-1)^(k+1)/prime(k)^2.

Cf. A136370: numerator of 1 - Sum_{k=1..n} (-1)^(k+1)/prime(k)^2.

Cf. A136365, A136366, A136367, A136369.

Programs

Mathematica

f=1; Do[ p=Prime[n]; f=f - (-1)^(n+1)*1/p^2; g=Numerator[f] ;If[ PrimeQ[g], Print[ {n, g} ] ], {n, 1, 100} ]

Python

# uses A136370gen() and imports from A136370
from sympy import isprime
def agen(): yield from (k for k, ak in enumerate(A136370gen(), 1) if isprime(ak))
print(list(islice(agen(), 5))) # Michael S. Branicky, Jun 26 2022

Extensions

More terms added and edited by Alexander Adamchuk, Sep 15 2010

a(10) from Robert Price, Aug 29 2019