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 A335105 #79 Mar 06 2022 09:04:46 %S A335105 1,2,1,3,1,3,5,6,1,3,5,7,1,3,5,7,9,10,1,3,5,7,9,11,1,3,5,7,9,12,1,3,5, %T A335105 7,9,13,1,3,5,7,9,14,1,3,5,7,9,15,1,3,5,7,9,15,18,19,1,3,5,7,9,15,18, %U A335105 20,1,3,5,7,9,15,18,20,23,24,1,3,5,7,9,15,18,20,23,25 %N A335105 Irregular triangle read by rows in which row n lists the partial sums of shell numbers and respective number of electrons for all occupied shells of the n-th element of the periodic table of the elements. %C A335105 The rows provide a way to distinguish the elements. %C A335105 Electron Configurations for elements after Nobelium (atomic number 102), whose configuration of [RN] 5f14 7s2 comprises the last row of sequence, are at present unknown (see CRC Handbook in References). %D A335105 Darleane C. Hoffman, Diana M. Lee, and Valeria Pershina, Transactinides and Future Elements, in Morss; Edelstein, Norman M.; Fuger, Jean (eds.). The Chemistry of Actinide and Transactinide Elements (3rd ed.). Dordrecht, The Netherlands (2006). %D A335105 Catherine E. Housecroft and Alan G. Sharpe, Inorganic Chemistry (5th ed.). Pearson Education Limited. Harlow, England. (2018). %D A335105 John R. Rumble (ed.), CRC Handbook of Chemistry and Physics, 100th edition. CRC Press. Boca Raton, Florida, 2019; Section 1, Electron Configuration and Ionization Energy of Neutral Atoms in the Ground State. %H A335105 David Williams, <a href="/A335105/b335105.txt">Table of n, a(n) for n = 1..200, for rows 1-23 and part of 24</a> %H A335105 Wikipedia, <a href="http://en.wikipedia.org/wiki/Electron_shell">Electron shell</a> %e A335105 Lithium 1s2 2s1 %e A335105 1+2+2+1 %e A335105 1,3,5,6 %e A335105 Thus: %e A335105 Hydrogen 1s1 1,2 %e A335105 Helium 1s2 1,3 %e A335105 Lithium 1s2 2s1 1,3,5,6 %e A335105 Beryllium 1s2 2s2 1,3,5,7 %e A335105 Boron 1s2 2s2 2p1 1,3,5,7,9,10 %Y A335105 Cf. A080915, A168208. %K A335105 nonn,tabf,fini %O A335105 1,2 %A A335105 _David Williams_, May 23 2020