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 A123754 #15 Sep 17 2017 22:32:42
%S A123754 3,63,99,195,255,399,483,575,675,783,1023,1155,1295,1443,1599,1935,
%T A123754 2115,2303,2499,2703,2915,3135,3363,3843,4095,4355,4623,4899,5475,
%U A123754 5775,6083,6399,6723,7055,7395,7743,8099,8463,8835,9215,9603,9999,10815
%N A123754 Positive numbers of the form 4*n^2 - 1 which are not semiprimes.
%C A123754 Positive numbers of the form 4*n^2 - 1 which are semiprimes can be found in A037074.
%C A123754 Or, all positive products of the form A014076(i)*[A014076(i)+-2], duplicates removed. - _R. J. Mathar_, Aug 08 2007
%H A123754 G. C. Greubel, <a href="/A123754/b123754.txt">Table of n, a(n) for n = 1..5000</a>
%F A123754 Equals ( A000466 - {-1} ) - A001358. - _R. J. Mathar_, Aug 08 2007
%t A123754 Select[4*(Range[54])^2-1, Not[PrimeQ[Sqrt[(#+ 1)]-1] && PrimeQ[Sqrt[(#+1)]+1]]&]
%t A123754 Select[4*Range[100]^2-1,PrimeOmega[#]!=2&] (* _Harvey P. Dale_, Jul 24 2016 *)
%Y A123754 Cf. A000466, A037074.
%K A123754 nonn
%O A123754 1,1
%A A123754 _Roger L. Bagula_, Nov 16 2006
%E A123754 Edited by _N. J. A. Sloane_, Aug 03 2007