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A147853
Least prime p such that there is a prime q with (p+q)/2=A002110(n), the n-th primorial.
1
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
2,1
COMMENTS
If q>10^22 then q is a probable prime. - Pierre CAMI, Jan 07 2014
EXAMPLE
For primorial=30, (p,q)=(7,53) as 7+53=2*30.
PROG
(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 }
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Bill McEachen, Nov 15 2008
EXTENSIONS
Improved description from T. D. Noe
STATUS
approved