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 A347251 #16 Aug 25 2021 07:41:09
%S A347251 1,-5,-28,16,-3126,47450,-823544,0,19683,10009766650,-285311670612,
%T A347251 -2176786432,-302875106592254,11112685048647250,437893920912786408,0,
%U A347251 -827240261886336764178,-101560344088905,-1978419655660313589123980,-100000000000001048576
%N A347251 a(n) = Sum_{d|n} mu(d)*mu(n/d)*d^n.
%H A347251 Seiichi Manyama, <a href="/A347251/b347251.txt">Table of n, a(n) for n = 1..388</a>
%F A347251 If p is prime, a(p) = -1 - p^p.
%t A347251 a[n_] := DivisorSum[n, MoebiusMu[#] * MoebiusMu[n/#] * #^n &]; Array[a, 20] (* _Amiram Eldar_, Aug 24 2021 *)
%o A347251 (PARI) a(n) = sumdiv(n, d, moebius(d)*moebius(n/d)*d^n);
%Y A347251 Diagonal of A347227.
%Y A347251 Cf. A007427, A008683, A046099, A067858, A321222.
%K A347251 sign
%O A347251 1,2
%A A347251 _Seiichi Manyama_, Aug 24 2021