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 A342828 #18 Mar 24 2021 09:51:55
%S A342828 1,0,2,-4,2,-11,2,-320,731,-2869,2,-1827,2,-819447,10297068,-33570816,
%T A342828 2,1775078476,2,-36222872973,678610493340,-285310622035,2,
%U A342828 169888943418701,95367431640627,-302875089815037,150094917726535604,-569376395999240231,2,104002456598734754865,2
%N A342828 a(n) = Sum_{d|n} (-1)^(n/d+1) * d^(n-d).
%H A342828 Seiichi Manyama, <a href="/A342828/b342828.txt">Table of n, a(n) for n = 1..599</a>
%F A342828 G.f.: Sum_{k>=1} x^k/(1 + (k * x)^k).
%F A342828 If p is an odd prime, a(p) = 2.
%t A342828 a[n_] := DivisorSum[n, (-1)^(n/# + 1) * #^(n - #) &]; Array[a, 30] (* _Amiram Eldar_, Mar 23 2021 *)
%o A342828 (PARI) a(n) = sumdiv(n, d, (-1)^(n/d+1)*d^(n-d));
%o A342828 (PARI) my(N=40, x='x+O('x^N)); Vec(sum(k=1, N, x^k/(1+(k*x)^k)))
%Y A342828 Cf. A308367, A321438, A342628.
%K A342828 sign
%O A342828 1,3
%A A342828 _Seiichi Manyama_, Mar 23 2021