A147853 Least prime p such that there is a prime q with (p+q)/2=A002110(n), the n-th primorial.

5, 7, 11, 17, 19, 19, 29, 37, 37, 37, 73, 47, 59, 71, 97, 79, 79, 101, 97, 137, 227, 137, 109, 127, 151, 127, 151, 151, 179, 227, 431, 139, 211, 223, 337, 181, 251, 257, 313, 227, 257, 227, 263, 491, 307, 241, 409, 263, 277

Offset: 2

Author

Bill McEachen, Nov 15 2008

Keywords

• easy
• nonn

Comments

If q>10^22 then q is a probable prime. - Pierre CAMI, Jan 07 2014

Examples

			For primorial=30, (p,q)=(7,53) as 7+53=2*30.
		

Links

• Pierre CAMI, Table of n, a(n) for n = 2..1376

Crossrefs

Cf. A002110, A147517

Programs

PARI

ospp(N)= { i=4; while(1, Q=2*N-prime(i); if( ispseudoprime(2*N-prime(i)),print(N,", ",prime(i) );return(1) ); i++ ); /* end WHILE */ }

Extensions

Improved description from T. D. Noe