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 A321236 #37 Nov 07 2018 10:04:05 %S A321236 1,5,28,17,3126,47450,823544,257,19684,10009766650,285311670612, %T A321236 2177317874,302875106592254,11112685048647250,437893920912786408, %U A321236 65537,827240261886336764178,101560344351050,1978419655660313589123980,100000095367432689202 %N A321236 a(n) = Sum_{d|n} mu(d)^2*d^n. %H A321236 Seiichi Manyama, <a href="/A321236/b321236.txt">Table of n, a(n) for n = 1..388</a> %F A321236 G.f.: Sum_{k>=1} mu(k)^2*(k*x)^k/(1 - (k*x)^k). %F A321236 a(n) = Product_{p|n, p prime} (1 + p^n). %t A321236 Table[Sum[MoebiusMu[d]^2 d^n, {d, Divisors[n]}], {n, 20}] %t A321236 nmax = 20; Rest[CoefficientList[Series[Sum[MoebiusMu[k]^2 (k x)^k/(1 - (k x)^k), {k, 1, nmax}], {x, 0, nmax}], x]] %t A321236 Table[Product[1 + Boole[PrimeQ[d]] d^n, {d, Divisors[n]}], {n, 20}] %o A321236 (PARI) a(n) = sumdiv(n, d, moebius(d)^2*d^n) \\ _Andrew Howroyd_, Nov 06 2018 %Y A321236 Cf. A008683, A048250, A320974, A321222. %K A321236 nonn %O A321236 1,2 %A A321236 _Ilya Gutkovskiy_, Nov 06 2018