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 A238127 #8 Feb 23 2014 05:05:54 %S A238127 0,0,0,1,2,6,17,57,191,663,2415,9108,35695,143989,599802,2566917, %T A238127 11298164,50967216,235745644,1115324000,5397332497,26669487517, %U A238127 134528555379,691856601631,3626390958551,19353306241764,105122093620388,580689432523534,3260906342453966 %N A238127 Number of standard Young tableaux with n cells and exactly two successions. %C A238127 A succession is a pair of cells (v, v+1) lying in the same row. %C A238127 Also number of ballot sequences having two flat steps. %C A238127 Third column (k=2) of A238125. %Y A238127 Cf. A237770 (no successions), A238126 (one succession). %K A238127 nonn %O A238127 0,5 %A A238127 _Joerg Arndt_ and _Alois P. Heinz_, Feb 21 2014