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 A282611 #20 Sep 08 2022 08:46:18
%S A282611 0,1,1,2,1,3,3,4,4,6,4,6,3,10,4,8,7,12,8,10,7,15,7,16,9,14,7,14,12,20,
%T A282611 13,16,13,23,13,18,12,28,16,20,16,24,12,28,17,30,13,24,20,32,19,32,16,
%U A282611 42,21,28,19,36,27,30,21,40,24,40,19,43,21,34,28,46
%N A282611 Expansion of q^(-1/3) * c(q) * c(q^3) / 9 in powers of q where c() is a cubic AGM theta function.
%C A282611 Cubic AGM theta functions: a(q) (see A004016), b(q) (A005928), c(q) (A005882).
%C A282611 G.f. is a period 1 Fourier series which satisfies f(-1 / (9 t)) = (t/i)^2 g(t) where g() is the g.f. for A282610.
%H A282611 G. C. Greubel, <a href="/A282611/b282611.txt">Table of n, a(n) for n = 0..5000</a>
%F A282611 Expansion of q^(-1/3) * eta(q^3)^2 * eta(q^9)^3 / eta(q) in powers of q.
%F A282611 Euler transform of period 9 sequence [1, 1, -1, 1, 1, -1, 1, 1, -4, ...].
%e A282611 G.f. = x + x^2 + 2*x^3 + x^4 + 3*x^5 + 3*x^6 + 4*x^7 + 4*x^8 + 6*x^9 + ...
%e A282611 G.f. = q^4 + q^7 + 2*q^10 + q^13 + 3*q^16 + 3*q^19 + 4*q^22 + 4*q^25 + ...
%t A282611 a[ n_] := SeriesCoefficient[ x QPochhammer[ x^3]^2 QPochhammer[ x^9]^3 / QPochhammer[ x], {x, 0, n}];
%o A282611 (PARI) {a(n) = if( n<1, 0, n--; my(A = x * O(x^n)); polcoeff( eta(x^3 + A)^2 * eta(x^9 + A)^3 / eta(x + A), n))};
%o A282611 (Magma) Basis( ModularForms( Gamma0(27), 2), 210)[5];
%Y A282611 Cf. A282610.
%K A282611 nonn
%O A282611 0,4
%A A282611 _Michael Somos_, Feb 19 2017