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 A134819 #16 Nov 30 2015 09:35:29 %S A134819 1,1,1,1,1,2,3,2,1,2,5,9,11,7,3,3,10,26,40,40,21,6,5,25,77,159,217, %T A134819 185,85,19,9,56,222,575,1031,1230,920,356,50,18,139,654,2082,4679, %U A134819 7437,7982,5308,1804,204,35,338,1902,7244,19983,40139,57771,56437,33860,10064,832 %N A134819 Irregular triangle read by rows: the number of hydrocarbon structures that can be drawn with a given number of carbons and units of unsaturation. %C A134819 Computed over a period of several years and confirmed using the Molgen program. %H A134819 David Consiglio, Jr., <a href="/A134819/b134819.txt">Table of n, a(n) for n = 1..130</a> %H A134819 Molgen, <a href="http://molgen.de/?src=documents/publications">Molecular Structure Generation</a> %e A134819 Triangle begins: %e A134819 1 %e A134819 1 1 1 %e A134819 1 2 3 2 1 %e A134819 2 5 9 11 7 3 %e A134819 etc. %e A134819 a(3,1) = 2 because there are two structures that contain 3 carbons and have 1 unit of unsaturation (propene and cyclopropane). %Y A134819 Row sums give A134818. %K A134819 nice,nonn,tabf %O A134819 1,6 %A A134819 _David Consiglio, Jr._, Jan 28 2008, Apr 23 2008