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 A109404 #11 May 01 2014 08:41:05
%S A109404 3,5,7,8,10,11,13,22,25,27,29,37,46,51,52,76,83,86,92,104,111,113,115,
%T A109404 123,132,140,149,190,213,218,222,233,242,274,280,281,286,298,303,307,
%U A109404 309,336,340,346,351,379,381,395,402,415,424,444,449,463,477,478,490
%N A109404 Numbers n such that sum of n-th and (n+1)-st semiprimes is a prime.
%e A109404 3 is OK because sp(3)=9, sp(3)=10 and 9+10=19 (prime); sp(n)=n-th semiprime.
%t A109404 With[{semis=Partition[Select[Range[2000],PrimeOmega[#]==2&],2,1]}, Flatten[ Position[ semis,_?(PrimeQ[Total[#]]&),{1},Heads->False]]] (* _Harvey P. Dale_, May 01 2014 *)
%o A109404 (PARI) lista(nn) = {vec = vector(nn, i, i); sp = select(i->(bigomega(i)==2), vec); for (i = 1, #sp-1, if (isprime(sp[i]+sp[i+1]), print1(i, ", ")););} \\ _Michel Marcus_, Oct 06 2013
%Y A109404 Cf. A092191 = numbers n such that sum of n-th and (n+1)-st semiprimes is a semiprime.
%K A109404 nonn
%O A109404 1,1
%A A109404 _Zak Seidov_, Jun 27 2005