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 A066798 #25 Jan 11 2025 12:32:10
%S A066798 20,944,49564,2753720,157871240,9233006540,547490880980,
%T A066798 32795094564080,1979734520212192,120244316085073616,
%U A066798 7339672750101339356,449852213026938118560,27666867082225970134160
%N A066798 a(n) = Sum_{i=1..n} binomial(6*i,3*i).
%H A066798 Harry J. Smith, <a href="/A066798/b066798.txt">Table of n, a(n) for n = 1..100</a>
%F A066798 G.f.: (1+8/s)^(3/2)*(s-4)*s^5/(3*(s^4+8*s^3-s+1)*(s^2+4*s-8)) - 1/(1-x) where (s+8)*s^3*x-s+1 = 0. - _Mark van Hoeij_, May 02 2013
%F A066798 a(n) ~ sqrt(3) * 64^(n+1) / (189*sqrt(Pi*n)). - _Vaclav Kotesovec_, Jun 07 2019
%F A066798 D-finite with recurrence n*(3*n-1)*(3*n-2)*a(n) +(-585*n^3+873*n^2-370*n+40)*a(n-1) +8*(6*n-5)*(6*n-1)*(2*n-1)*a(n-2)=0. - _R. J. Mathar_, Jan 11 2025
%p A066798 s := RootOf((s+8)*s^3*x-s+1, s):
%p A066798 series( (1+8/s)^(3/2)*(s-4)*s^5/(3*(s^4+8*s^3-s+1)*(s^2+4*s-8)) - 1/(1-x), x=0, 30); # _Mark van Hoeij_, May 02 2013
%t A066798 Accumulate[Table[Binomial[6n,3n],{n,20}]] (* _Harvey P. Dale_, Apr 04 2020 *)
%o A066798 (PARI) { a=0; for (n=1, 100, write("b066798.txt", n, " ", a+=binomial(6*n, 3*n)) ) } \\ _Harry J. Smith_, Mar 28 2010
%Y A066798 Cf. A006134, A066796, A066797, A066802.
%K A066798 nonn
%O A066798 1,1
%A A066798 _Benoit Cloitre_, Jan 18 2002