A265126 - OEIS

A265126

Integers n such that either 2^n * prime(n) + 3 or 2^n * prime(n) - 3 is prime.

1, 3, 4, 5, 6, 7, 8, 9, 12, 17, 18, 19, 21, 23, 25, 33, 34, 37, 39, 41, 46, 52, 55, 58, 60, 66, 91, 126, 158, 191, 222, 444, 529, 590, 649, 751, 925, 1082, 1313, 2094, 2269, 2424, 2572, 2923, 3732, 4009, 4172, 4207, 4521, 4866, 5125, 5617, 8583, 9032, 16235, 18492

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

LINKS

Table of n, a(n) for n=1..56.

EXAMPLE

1 is a term because 2^1 * 2 + 3 = 7 is prime.

4 is a term because 2^4 * 7 - 3 = 109 is prime.

MATHEMATICA

Select[Range@ 5000, Or[PrimeQ[2^# Prime@ # + 3], PrimeQ[2^# Prime@ # - 3]] &] (* Michael De Vlieger, Dec 02 2015 *)

PROG

(PARI) for(n=1, 1e4, if(ispseudoprime(2^n*prime(n) - 3) || ispseudoprime(2^n*prime(n) + 3), print1(n, ", ")));