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 A228877 #3 Sep 24 2013 21:48:22 %S A228877 30,60,216,336,486,546,726,756,1350,1716,2166,8670,8976,10086,10296, %T A228877 12150,15606,18150,24576,28566,30246,34656,37050,37446,47526,52026, %U A228877 59340,68040,71610,73926,74256,80730,80736,82140,99846,107736,118326,124416,155526,169830 %N A228877 Upper Pythagorean twins. %Y A228877 Cf. A228875. %K A228877 nonn %O A228877 1,1 %A A228877 _T. D. Noe_, Sep 24 2013