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 A138726 #6 Apr 16 2014 00:27:55 %S A138726 1,3,11,19,37,55,87,119,169,219,291,4,12,20,38,56,88,120,170,220,292, %T A138726 21,39,57,89,121,171,221,293,58,90,122,172,222,294,123,173,223,295, %U A138726 224,296,225,297,226,298,227,299,228,300,229,301,230,302,231,303,232,304,233 %N A138726 Atomic numbers of the periodic table of the elements, read downwards along 72 columns, up to the 11th period. %C A138726 This finite sequence has 362 members. Atomic numbers > 362 are not members. %e A138726 ======================================================================== %e A138726 ............................ STRUCTURE OF ............................. %e A138726 ................. THE PERIODIC TABLE OF THE ELEMENTS .................. %e A138726 ............................ (72 columns) ............................. %e A138726 ======================================================================== %e A138726 X......................................................................X %e A138726 XX................................................................XXXXXX %e A138726 XX................................................................XXXXXX %e A138726 XXX......................................................XXXXXXXXXXXXXXX %e A138726 XXX......................................................XXXXXXXXXXXXXXX %e A138726 XXXX........................................XXXXXXXXXXXXXXXXXXXXXXXXXXXX %e A138726 XXXX........................................XXXXXXXXXXXXXXXXXXXXXXXXXXXX %e A138726 XXXXX......................XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX %e A138726 XXXXX......................XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX %e A138726 XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX %e A138726 XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX %e A138726 ======================================================================== %Y A138726 Cf. A099955, A134984, A138723, A138724, A138725. %K A138726 fini,nonn %O A138726 1,2 %A A138726 _Omar E. Pol_, Apr 09 2008