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 A249947 #15 Nov 25 2014 23:04:22 %S A249947 1,1,3,1,3,1,5,3,1,5,3,1,7,5,3,1,7,5,3 %N A249947 Number of available orbitals at increasing subshells in multi-electron atoms. %C A249947 Follows electron configuration in a multi-electron atom, which is: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p. Each s subshell holds 1 orbital, each p holds 3 orbitals, each d holds 5 orbitals, and each f holds 7 orbitals. %C A249947 Theoretically, the integers follow the pattern infinitely, but (conjecturally) the subshells stop after 7p, with 8s not existing as predicted. %H A249947 ChemWiki, <a href="http://chemwiki.ucdavis.edu/Inorganic_Chemistry/Electronic_Configurations">Electron configurations</a> %H A249947 ChemWiki, <a href="http://chemwiki.ucdavis.edu/Physical_Chemistry/Quantum_Mechanics/10._Multi-electron_Atoms/Quantum_Numbers?bc=1">Quantum numbers</a> %e A249947 1s %e A249947 2s 2p %e A249947 3s 3p 3d %e A249947 4s 4p 4d 4f %e A249947 5s 5p 5d 5f %e A249947 6s 6p 6d %e A249947 7s 7p %e A249947 (8s) %e A249947 Read antidiagonals. %Y A249947 Cf. A167268. %K A249947 nonn,full,fini %O A249947 1,3 %A A249947 _Max Alweiss_, Nov 08 2014