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 A215549 #9 Feb 08 2017 18:35:36 %S A215549 0,4862,2466750,63882940,670609940,4277470470,19794795118,73143988775, %T A215549 228723580800,628737007195,1559830082888,3559370252529,7576971259000, %U A215549 15210525840125,29040055455840,53087119860346,93432350566520,159028880903100,262755041438890 %N A215549 Number of standard Young tableaux of shape [9n,9]. %C A215549 Also the number of binary words with 9n 1's and 9 0's such that for every prefix the number of 1's is >= the number of 0's. %H A215549 Alois P. Heinz, <a href="/A215549/b215549.txt">Table of n, a(n) for n = 0..1000</a> %H A215549 Wikipedia, <a href="https://en.wikipedia.org/wiki/Young_tableau">Young tableau</a> %F A215549 G.f.: (8*x^9 -80*x^8 +37540*x^7 +3833365*x^6 +48377194*x^5 +151114390*x^4 +142200850*x^3 +39434230*x^2 +2418130*x +4862)*x / (x-1)^10. %F A215549 a(n) = C(9*n+9,9)*(9*n-8)/(9*n+1) for n>0, a(0) = 0. %p A215549 a:= n-> max(0, binomial(9*n+9,9)*(9*n-8)/(9*n+1)): %p A215549 seq(a(n), n=0..30); %Y A215549 Row n=9 of A214776. %K A215549 nonn %O A215549 0,2 %A A215549 _Alois P. Heinz_, Aug 16 2012