A156148 Numbers k such that prime(prime(k)) + 2 == 0 (mod prime(k)), where prime(p)=A000040(p) is the p-th prime.

5, 20, 51891, 51893

Offset: 1

Author

M. F. Hasler, Feb 04 2009

Keywords

• hard
• more
• nonn

Comments

No additional terms up to k=500,000. - Harvey P. Dale, Jul 12 2022

Crossrefs

Cf. A156155.

Programs

Mathematica

Select[Range[52000],Mod[Prime[Prime[#]]+2,Prime[#]]==0&] (* Harvey P. Dale, Jul 12 2022 *)

PARI

p=c=0; until(0, until( isprime(c++), p=nextprime(p+1)); (p+2)%c & next; print1( primepi(c)","))

Formula

a(n) = A000720(A156149(n)).