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 A215551 #18 Aug 29 2025 04:14:07
%S A215551 1,6,77,1120,17199,272272,4395118,71916768,1188576675,19794795118,
%T A215551 331670995656,5584693695280,94418718611490,1601780734932840,
%U A215551 27253077978559384,464859662065426880,7946606112855555915,136106890528701061242,2335187812028912966125
%N A215551 a(n) = binomial(7*n,n)*(5*n+1)/(6*n+1).
%C A215551 Number of standard Young tableaux of shape [6n,n].
%H A215551 Alois P. Heinz, <a href="/A215551/b215551.txt">Table of n, a(n) for n = 0..250</a>
%H A215551 Wikipedia, <a href="https://en.wikipedia.org/wiki/Young_tableau">Young tableau</a>.
%F A215551 a(n) = C(7*n,n)*(5*n+1)/(6*n+1).
%F A215551 a(n) = [x^n] ((1 - sqrt(1 - 4*x))/(2*x))^(5*n+1). - _Ilya Gutkovskiy_, Nov 01 2017
%F A215551 a(n) ~ sqrt(3) * 5 * 7^(7*n+1/2) / (6^(6*n+2) * sqrt(Pi*n)). - _Amiram Eldar_, Aug 29 2025
%p A215551 a:= n-> binomial(7*n,n)*(5*n+1)/(6*n+1):
%p A215551 seq(a(n), n=0..20);
%t A215551 Table[Binomial[7n,n] (5n+1)/(6n+1),{n,0,30}] (* _Harvey P. Dale_, Apr 30 2022 *)
%Y A215551 Column k=6 of A214776.
%K A215551 nonn,changed
%O A215551 0,2
%A A215551 _Alois P. Heinz_, Aug 15 2012