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 A112888 #6 Jun 01 2016 19:01:03
%S A112888 9,33,91,299,213,1383,3091,8129
%N A112888 Least semiprime of a cluster of just n semiprimes.
%C A112888 Clusters are sets composed of odd numbers.
%C A112888 If we include even numbers then the sequence would start 4,9,33 and terminates because in any group of four consecutive numbers greater than 4, 4 is a divisor to at least one member leaving a quotient greater than 1.
%C A112888 Any set of 9 consecutive odd numbers contain a multiple of 9, which not semiprime (unless it is equal to 9). Hence there are no 9 consecutive odd semiprimes.
%e A112888 a(8)=8129 because 8129=11*739, 8131=47*173, 8133=3*2711, 8135=5*1627, 8137=79*103, 8139=3*2713, 8141=7*1163, 8143=17*479.
%t A112888 spQ[n_] := Plus @@ Last /@ FactorInteger@n == 2; f[n_] := Block[{k = 1}, While[ s[[k]] + 2n != s[[k + n]] || s[[k]] + 2n + 2 == s[[k + n + 1]], k++ ]; s[[k]]]; s = {}; Do[ If[ spQ[n], AppendTo[s, n]], {n, 9, 7*10^6, 2}]; Table[ f[n], {n, 0, 7}]
%t A112888 Join[{9},Module[{osps=Select[Range[9,10001,2],PrimeOmega[#]==2&]}, #[[2]]& /@ Table[ SelectFirst[Partition[osps,n+2,1],Union[ Differences[ Rest[ Most[#]]]]=={2}&&Last[#]-#[[-2]]!=2&&#[[2]]-#[[1]]!=2&],{n,2,8}]]] (* _Harvey P. Dale_, Jun 01 2016 *)
%Y A112888 Cf. A001358, A097824, A082919.
%K A112888 nonn,fini,full
%O A112888 1,1
%A A112888 _Robert G. Wilson v_, Nov 30 2005
%E A112888 fini, full from _Max Alekseyev_, Feb 03 2010