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 A306157 #21 Apr 13 2025 07:23:58
%S A306157 3,6,8,24,48,124,312,834,2184,5928,16104,44344,122640,341796,956576,
%T A306157 2690844,7596480,21524412,61171656,174342192,498111952,1426419852,
%U A306157 4093181688,11767919284,33891544368,97764131640,282429535752,817028472936,2366564736720,6863038212784
%N A306157 Inverse Weigh transform of 3^n.
%H A306157 Seiichi Manyama, <a href="/A306157/b306157.txt">Table of n, a(n) for n = 1..2000</a>
%H A306157 Christian G. Bower, <a href="https://oeis.org/transforms_pari.txt">PARI programs for transforms</a>, 2007.
%H A306157 N. J. A. Sloane, <a href="/transforms.txt">Maple programs for transforms</a>, 2001-2020.
%F A306157 Product_{k>=1} (1+x^k)^a(k) = 1/(1-3x).
%F A306157 a(n) = (1/n) * (3^n + Sum_{d<n and d|n} (-1)^(n/d) * d * a(d)).
%e A306157 (1+x)^3*(1+x^2)^6*(1+x^3)^8*(1+x^4)^24* ... = 1 + 3*x + 9*x^2 + 27*x^3 + 81*x^4 + ... .
%Y A306157 Inverse Weigh transform of b^n: A306156 (b=2), this sequence (b=3), A306158 (b=4), A306159 (b=5).
%Y A306157 Cf. A000244, A038068.
%K A306157 nonn
%O A306157 1,1
%A A306157 _Seiichi Manyama_, Jun 23 2018