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 A075278 #6 Mar 30 2012 17:26:03
%S A075278 6,9,15,21,39,69,93,111,129,309,381,393,453,489,501,687,723,771,879,
%T A075278 933,939,1011,1167,1299,1527,1563,1569,1839,1941,1983,2157,2217,2229,
%U A075278 2271,2391,2463,2661,2811,2859,2913,3039,3099,3189,3453,3459,3651,3849
%N A075278 Interprimes which are of the form s*prime, s=3.
%C A075278 Interprimes which are of the form s*prime are in A075277-A075296 (s = 2-21). Case s = 1 is impossible.
%e A075278 39 is an interprime and 39/3 = 13 is prime.
%t A075278 s=3; Select[Table[(Prime[n+1]+Prime[n])/2, {n, 2, 1000}], PrimeQ[ #/s]&]
%Y A075278 Cf. A075277--A075296.
%K A075278 easy,nonn
%O A075278 1,1
%A A075278 _Zak Seidov_, Sep 12 2002