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 A131181 #16 May 16 2013 09:47:52
%S A131181 6,8,10,12,14,15,18,20,21,22,26,27,28,32,33,34,35,36,38,39,44,45,46,
%T A131181 48,50,51,52,55,57,58,60,62,63,64,65,68,69,72,74,75,76,77,80,82,84,85,
%U A131181 86,87,90,91,92,93,94,95,96,98,99,100,106,108,111,112,115,116,117,118,119,120,122,123,124,125,126,129,132,133,134,140,141,142,143,144,145,146,147,148,150,153,155,156,158,159,160,161,162,164,166,168,171,172,175,176,177,178,183
%N A131181 A 2-way classification of integers: complement of A026416.
%C A131181 The sequence contains (for example) 140, so differs from A000379 by more than just the missing term 1. - _Vladimir Shevelev_, Apr 05 2013
%t A131181 f[1]=1; f[2]=2; f[n_] := f[n] = For[k = f[n-1]+1, True, k++, If[ FreeQ[ Table[ f[i]*f[j], {i, 1, n-2}, {j, i+1, n-1}], k], Return[k]]];
%t A131181 A026416 = Table[f[n], {n, 1, 80}];
%t A131181 A131181 = Complement[ Range[ A026416 // Last], A026416] (* _Jean-François Alcover_, May 16 2013 *)
%Y A131181 Complement of A026416.
%Y A131181 Cf. A000379.
%K A131181 nonn,easy
%O A131181 1,1
%A A131181 _Max Alekseyev_, Sep 23 2007