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

Author

K. D. Bajpai, Jan 29 2014

Keywords

• nonn

Examples

			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.
		

Links

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

Crossrefs

Cf. A000040, A234695, A236119.

Programs

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);

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