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 A082131 #17 Jul 17 2017 10:26:01
%S A082131 93,121,143,185,203,215,217,219,289,301,303,321,393,413,415,471,517,
%T A082131 535,581,669,687,697,791,815,1057,1079,1135,1137,1139,1147,1167,1205,
%U A082131 1255,1315,1345,1347,1349,1385,1387,1389,1391,1403,1563,1641,1687
%N A082131 Middle of semiprime triple: n-2, n, n+2 are semiprimes.
%C A082131 All terms are odd. - _David A. Corneth_, Jul 16 2017
%H A082131 Harvey P. Dale and David A. Corneth, <a href="/A082131/b082131.txt">Table of n, a(n) for n = 1..13739</a> (terms < 10^6, first 1000 terms from Harvey P. Dale)
%e A082131 a(1) = 93 because 91 = 7*13, 93 = 3*31 and 95 = 5*19 are semiprime.
%t A082131 2#+1&/@Flatten[Position[Partition[If[PrimeOmega[#]==2,1,0]&/@Range[ 1,1701,2],3,1],_?(Total[#]==3&),{1},Heads->False]] (* _Harvey P. Dale_, Jul 24 2013 *)
%o A082131 (PARI) isok(n) = (bigomega(n-2) == 2) && (bigomega(n)==2) && (bigomega(n+2) == 2); \\ _Michel Marcus_, Jul 16 2017
%o A082131 (PARI) list(lim)={my(u=primes(primepi(lim\3)), v=List(), t, res = List()); for(i=2, #u, for(j=i, #u, t=u[i]*u[j]; if(t>lim, break); listput(v, t))); listsort(v); for(i=1, #v-2, if(v[i]+4==v[i+2],listput(res,v[i+1]))); res} \\ adapted from _Charles R. Greathouse IV_ at A046315. - _David A. Corneth_, Jul 16 2017
%Y A082131 Cf. A001358, A046315, A082130.
%K A082131 nonn
%O A082131 1,1
%A A082131 _Hugo Pfoertner_, Apr 04 2003
%E A082131 More terms from _Jud McCranie_, Apr 04 2003