This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A195377 #17 Aug 03 2014 14:01:33 %S A195377 127,197,281,311,347,431,613,659,673,739,877,991,1049,1229,1277,1289, %T A195377 1367,1481,1579,1613,1667,1721,1787,1877,1907,2027,2081,2087,2141, %U A195377 2203,2213,2237,2239,2269,2287,2309,2377,2383,2473,2657,2689,2707,2749,2767,2801 %N 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. %t A195377 Select[Prime[Range[500]], PrimePi[5*NextPrime[#]/2] == PrimePi[5*#/2] &] (* _T. D. Noe_, Sep 20 2011 *) %Y A195377 Cf. A195270, A195271, A195325, A194658, A164294. %K A195377 nonn %O A195377 1,1 %A A195377 _Vladimir Shevelev_, Sep 17 2011