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 A139640 #3 Mar 31 2012 10:22:09 %S A139640 151,487,727,751,1039,1063,1399,1471,1759,1783,2287,2647,2671,2767, %T A139640 3343,3463,3919,4111,4423,4663,4903,4999,5167,5407,5791,6607,6703, %U A139640 6823,7159,7351,7639,7879,8191,8263,8311,8839,9127,9151,9439,9967,10111,10711 %N A139640 Numbers of the form of 4x^2 - 4xy + 7y^2 (=24k+7) but not of the form 4x^2 + 4xy + 7y^2. %C A139640 Numbers which occur in A107006 but not in A107005. %Y A139640 Cf. A107005, A107006. %K A139640 nonn %O A139640 1,1 %A A139640 _Artur Jasinski_, Apr 28 2008 %E A139640 More terms from _T. D. Noe_, May 01 2008