A236687 Primes p such that prime(p^2) - 2 is also prime.

2, 11, 17, 47, 61, 137, 163, 229, 239, 263, 317, 389, 419, 449, 467, 557, 571, 617, 619, 653, 709, 937, 953, 1009, 1033, 1087, 1123, 1129, 1181, 1249, 1481, 1831, 1987, 2003, 2099, 2207, 2381, 2441, 2579, 2663, 2707, 3109, 3457, 3833, 4013, 4463, 4519, 4783

Offset

1,1

Links

K. D. Bajpai, Table of n, a(n) for n = 1..564

Example

17 is prime and appears in the sequence because prime(17^2) = 1879 and 1879 - 2 = 1877, which is also prime.
47 is prime and appears in the sequence because prime(47^2) = 19471 and 19471 - 2 = 19469, which is also prime.

Maple

KD := proc() local a, b, d; a:=ithprime(n); b:=ithprime(a^2)-2; if isprime (b) then RETURN (a); fi; end: seq(KD(), n=1..500);

Prog

(PARI)
default(primelimit, 2^31)
s=[]; forprime(p=2, 5000, if(isprime(prime(p^2)-2), s=concat(s, p))); s \\ Colin Barker, Jan 30 2014

Crossrefs

Cf. A000040, A234695, A236119.

Sequence in context: A296053 A234647 A106949 * A187762 A217306 A106981

Adjacent sequences: A236684 A236685 A236686 * A236688 A236689 A236690

Keyword

nonn

Author

K. D. Bajpai, Jan 29 2014

Status

approved