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 A346577 #9 Jul 25 2021 02:41:01
%S A346577 1,2,9,40,200,1026,5537,30624,173583,1001400,5864749,34768296,
%T A346577 208267319,1258574114,7663720500,46976003712,289628805622,
%U A346577 1794932293950,11175157356521,69864074596000,438403736543598,2760351027094298,17433869214973753,110420300844952992
%N A346577 a(n) = (1/(3*n)) * Sum_{d|n} mu(n/d) * binomial(3*d,d).
%C A346577 Inverse Euler transform of A001764.
%C A346577 Moebius transform of A082936.
%F A346577 a(n) = A060170(n)/3. - _Hugo Pfoertner_, Jul 24 2021
%t A346577 Table[(1/(3 n)) Sum[MoebiusMu[n/d] Binomial[3 d, d], {d, Divisors[n]}], {n, 24}]
%o A346577 (PARI) a(n) = sumdiv(n, d, moebius(n/d)*binomial(3*d,d))/(3*n); \\ _Michel Marcus_, Jul 24 2021
%Y A346577 Cf. A001764, A005809, A008683, A022553, A060170, A082936, A346578, A346579, A346580, A346581, A346582.
%K A346577 nonn
%O A346577 1,2
%A A346577 _Ilya Gutkovskiy_, Jul 24 2021