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 A034741 #26 Dec 11 2020 03:58:59
%S A034741 1,2,8,24,80,232,728,2160,6552,19600,59048,176880,531440,1593592,
%T A034741 4782880,14346720,43046720,129133368,387420488,1162241760,3486783664,
%U A034741 10460294152,31381059608,94142999520,282429536400,847288078000,2541865821768,7625595890640,22876792454960
%N A034741 Dirichlet convolution of mu(n) with 3^(n-1).
%H A034741 Seiichi Manyama, <a href="/A034741/b034741.txt">Table of n, a(n) for n = 1..2096</a>
%F A034741 G.f.: Sum_{k>=1} mu(k)*x^k/(1 - 3*x^k). - _Ilya Gutkovskiy_, Oct 25 2018
%F A034741 a(n) ~ 3^(n-1). - _Vaclav Kotesovec_, Sep 11 2019
%t A034741 nmax = 20; Rest[CoefficientList[Series[Sum[MoebiusMu[k] * x^k / (1 - 3*x^k), {k, 1, nmax}], {x, 0, nmax}], x]] (* _Vaclav Kotesovec_, Dec 11 2020 *)
%o A034741 (PARI) a(n) = sumdiv(n,d, moebius(d) * 3^(n/d-1) ); \\ _Joerg Arndt_, Apr 14 2013
%Y A034741 Column k=3 of A143325.
%Y A034741 First differences of A320087.
%Y A034741 Cf. A054718.
%K A034741 nonn
%O A034741 1,2
%A A034741 _Erich Friedman_