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 A038068 #19 Apr 13 2025 07:20:38
%S A038068 3,-3,8,-21,48,-116,312,-831,2184,-5880,16104,-44336,122640,-341484,
%T A038068 956576,-2690841,7596480,-21522228,61171656,-174342144,498111952,
%U A038068 -1426403748,4093181688,-11767919276,33891544368,-97764009000
%N A038068 Product_{k>=1}(1 + x^k)^a(k) = 1 + 3x.
%H A038068 Seiichi Manyama, <a href="/A038068/b038068.txt">Table of n, a(n) for n = 1..2000</a>
%H A038068 Christian G. Bower, <a href="https://oeis.org/transforms_pari.txt">PARI programs for transforms</a>, 2007.
%H A038068 N. J. A. Sloane, <a href="/transforms.txt">Maple programs for transforms</a>, 2001-2020.
%F A038068 Dirichlet convolution of A038064 with characteristic function of powers of 2.
%F A038068 a(n) = (1/n) * (-(-3)^n + Sum_{d<n and d|n} (-1)^(n/d) * d * a(d)). - _Seiichi Manyama_, Jun 23 2018
%Y A038068 Cf. A038063-A038070, A306157.
%K A038068 sign
%O A038068 1,1
%A A038068 _Christian G. Bower_, Jan 04 1999