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 A321222 #22 Nov 07 2018 10:03:42
%S A321222 1,-3,-26,-15,-3124,45864,-823542,-255,-19682,9990233352,
%T A321222 -285311670610,2176246800,-302875106592252,11111328602468784,
%U A321222 437893859848932344,-65535,-827240261886336764176,101559568985784,-1978419655660313589123978,99999904632567310800
%N A321222 a(n) = Sum_{d|n} mu(d)*d^n.
%H A321222 Seiichi Manyama, <a href="/A321222/b321222.txt">Table of n, a(n) for n = 1..388</a>
%F A321222 G.f.: Sum_{k>=1} mu(k)*(k*x)^k/(1 - (k*x)^k).
%F A321222 a(n) = Product_{p|n, p prime} (1 - p^n).
%t A321222 Table[Sum[MoebiusMu[d] d^n, {d, Divisors[n]}], {n, 20}]
%t A321222 nmax = 20; Rest[CoefficientList[Series[Sum[MoebiusMu[k] (k x)^k/(1 - (k x)^k), {k, 1, nmax}], {x, 0, nmax}], x]]
%t A321222 Table[Product[1 - Boole[PrimeQ[d]] d^n, {d, Divisors[n]}], {n, 20}]
%o A321222 (PARI) a(n) = sumdiv(n, d, moebius(d)*d^n) \\ _Andrew Howroyd_, Nov 06 2018
%Y A321222 Cf. A008683, A023900, A046970, A063453, A067858, A189922, A189923.
%K A321222 sign
%O A321222 1,2
%A A321222 _Ilya Gutkovskiy_, Nov 06 2018