A195377 2.5-gap primes: Prime p is a term if there is no prime between 2.5*p and 2.5*q, where q is the next prime after p.

127, 197, 281, 311, 347, 431, 613, 659, 673, 739, 877, 991, 1049, 1229, 1277, 1289, 1367, 1481, 1579, 1613, 1667, 1721, 1787, 1877, 1907, 2027, 2081, 2087, 2141, 2203, 2213, 2237, 2239, 2269, 2287, 2309, 2377, 2383, 2473, 2657, 2689, 2707, 2749, 2767, 2801

Offset: 1

Author

Vladimir Shevelev, Sep 17 2011

Keywords

• nonn

Crossrefs

Cf. A195270, A195271, A195325, A194658, A164294.

Programs

Mathematica

Select[Prime[Range[500]], PrimePi[5*NextPrime[#]/2] == PrimePi[5*#/2] &] (* T. D. Noe, Sep 20 2011 *)