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 A344210 #40 Apr 03 2025 09:52:01
%S A344210 1,3,13,120,781,22932,137257,4177920,64566801,2497558338,28531167061,
%T A344210 2228476723200,25239592216021,1851888100411464,54736732481116543,
%U A344210 2305807824841605120,51702516367896047761,6557709646516945221396,109912203092239643840221
%N A344210 a(n) = Sum_{d|n} mu(n/d) * d^n / phi(n).
%F A344210 a(n) = J_n(n) / phi(n) = A067858(n) / A000010(n).
%F A344210 a(n) = (1/n) * Sum_{d|n} mu(n/d)*sigma(d^n). - _Ridouane Oudra_, Apr 03 2025
%t A344210 Table[DivisorSum[n,MoebiusMu[n/#]*#^n/EulerPhi[n]&],{n,20}] (* _Giorgos Kalogeropoulos_, May 13 2021 *)
%o A344210 (PARI) a(n) = sumdiv(n, d, moebius(n/d)*d^n)/eulerphi(n);
%Y A344210 Main diagonal of A263950.
%Y A344210 Cf. A000010, A067858, A008683, A000203.
%K A344210 nonn
%O A344210 1,2
%A A344210 _Seiichi Manyama_, May 12 2021