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 A385284 #16 Jun 26 2025 08:08:57
%S A385284 1,1,4,1,-152,-3515,-54080,-671363,-2823296,199955305,10101514240,
%T A385284 323321153881,7583054076928,80180394219757,-4570380001660928,
%U A385284 -409907196093564395,-20705306119297925120,-748794938843475359663,-14289862480447260852224,610587389113316064978481
%N A385284 Expansion of e.g.f. 1/(1 - 3 * x * cos(3*x))^(1/3).
%F A385284 a(n) = Sum_{k=0..n} A007559(k) * (3*i)^(n-k) * A185951(n,k), where i is the imaginary unit and A185951(n,0) = 0^n.
%o A385284 (PARI) a185951(n, k) = binomial(n, k)/2^k*sum(j=0, k, (2*j-k)^(n-k)*binomial(k, j));
%o A385284 a007559(n) = prod(k=0, n-1, 3*k+1);
%o A385284 a(n) = sum(k=0, n, a007559(k)*(3*I)^(n-k)*a185951(n, k));
%Y A385284 Cf. A352252, A385283.
%Y A385284 Cf. A007559, A185951.
%K A385284 sign
%O A385284 0,3
%A A385284 _Seiichi Manyama_, Jun 24 2025