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 A109310 #7 Oct 06 2013 07:56:16
%S A109310 4,6,18,21,23,30,36,42,43,50,68,76,78,80,87,88,91,98,108,111,116,117,
%T A109310 118,120,127,128,134,138,141,150,151,152,153,156,164,168,171,179,185,
%U A109310 186,192,195,196,204,212,215,216,226,232,236,237,244,245,250,255,266
%N A109310 Numbers n such that difference between n-th and (n+1)-st semiprimes is a semiprime (sp).
%e A109310 4 is ok because sp(4)=10, sp(5)=14, 14-10=sp(1), sp(n)=A001358(n)=n-th semiprime.
%o A109310 (PARI) lista(nn) = {vec = vector(nn, i, i); sp = select(i->(bigomega(i)==2), vec); for (i = 1, #sp-1, if (bigomega(sp[i+1]-sp[i]) == 2, print1(i, ", ")););} \\ _Michel Marcus_, Oct 06 2013
%Y A109310 Cf. A001358 = Semiprimes, A092191 = numbers n such that sum of n-th and (n+1)-st semiprimes is a semiprime.
%K A109310 nonn
%O A109310 1,1
%A A109310 _Zak Seidov_, Jun 27 2005