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 A099956 #5 Mar 30 2012 17:25:42 %S A099956 4,12,20,38,56,88 %N A099956 Atomic numbers of the alkaline earth metals. %e A099956 12 is the atomic number of magnesium. %Y A099956 Cf. A099955, alkali metals; A101648, metalloids; A101647, nonmetals (except halogens and noble gases); A097478, halogens; A018227, noble gases; A101649, poor metals. %K A099956 nonn,fini,full %O A099956 1,1 %A A099956 _Parthasarathy Nambi_, Nov 12 2004