A164622 Primes p such that p*floor(p/2) - 4 and p*floor(p/2) + 4 are prime numbers.

151, 463, 571, 631, 643, 991, 1063, 1171, 1831, 2083, 2311, 4951, 5023, 6211, 6703, 6763, 7723, 7951, 9043, 11383, 12163, 12391, 13183, 14851, 15031, 17431, 19231, 19543, 20143, 22051, 23143, 25951, 26371, 27283, 28351, 29131, 30643, 32803

Offset: 1

Author

Vladimir Joseph Stephan Orlovsky, Aug 17 2009

Keywords

• nonn

Comments

151*75-4=11321 (prime), 151*75+4=11329 (prime), ..

Crossrefs

Subsequence of A068229. Cf. A008846, A020882, A068229, A086519, A158708, A164620, A164621

Programs

Mathematica

lst={};Do[p=Prime[n];If[PrimeQ[p*Floor[p/2]-4]&&PrimeQ[p*Floor[p/2]+4],AppendTo[lst,p]],{n,8!}];lst

Extensions

Edited by Charles R Greathouse IV, Nov 02 2009