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 A087350 #6 Jan 27 2020 18:48:21
%S A087350 1,7,841,423865,559501801,1527439916731,7478345832314977,
%T A087350 59677199741873516461,724719913665311983902385,
%U A087350 12718834484826225317486856751,309830808050366848733979830454361,10142621332336809160155563729753961697,434509897877308904421064350182659719099481
%N A087350 a(n) = Sum_{k=0..n} (3*n)!/(3*k)!.
%H A087350 Andrew Howroyd, <a href="/A087350/b087350.txt">Table of n, a(n) for n = 0..100</a>
%F A087350 a(n) = floor((3*n)!*C) where C = 1/3*exp(1)+2/3*exp(-1/2)*cos(1/2*3^(1/2)) = 1.16805831337591852551625692...
%o A087350 (PARI) a(n)={sum(k=0, n, (3*n)!/(3*k)!)} \\ _Andrew Howroyd_, Jan 27 2020
%Y A087350 Cf. A000522, A051396.
%K A087350 nonn
%O A087350 0,2
%A A087350 _Vladeta Jovovic_, Oct 20 2003
%E A087350 Terms a(11) and beyond from _Andrew Howroyd_, Jan 27 2020