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 A372939 #7 May 17 2024 09:51:13
%S A372939 1,7,53,736,6249,185039,1647085,66912256,1162222101,39980466703,
%T A372939 570623341221,53487845236736,605750213184505,44446670856053599,
%U A372939 1751575500459583437,92232594468640915456,1654480523772673528353,236077997761634282622495
%N A372939 a(n) = Sum_{1 <= x_1, x_2, ... , x_n <= n} gcd(x_1, x_2, ... , x_n, n)^n.
%F A372939 a(n) = Sum_{d|n} mu(n/d) * d^n * tau(d), where mu is the Moebius function A008683.
%o A372939 (PARI) a(n) = sumdiv(n, d, moebius(n/d)*d^n*numdiv(d));
%Y A372939 Main diagonal of A372938.
%Y A372939 Cf. A000005, A008683.
%K A372939 nonn
%O A372939 1,2
%A A372939 _Seiichi Manyama_, May 17 2024