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 A344525 #21 Aug 05 2024 09:39:25
%S A344525 1,5,30,276,3165,47521,826000,16843792,387723045,10009889889,
%T A344525 285360865350,8918311872516,302888304741841,11112685595264369,
%U A344525 437898699063881208,18447025862624951488,827242515246907227633,39346558373191515582161
%N A344525 a(n) = Sum_{1 <= x_1, x_2, ... , x_n <= n} gcd(x_1,x_2, ... ,x_n).
%H A344525 Seiichi Manyama, <a href="/A344525/b344525.txt">Table of n, a(n) for n = 1..386</a>
%F A344525 a(n) = Sum_{k=1..n} phi(k) * floor(n/k)^n.
%F A344525 a(n) ~ n^n. - _Vaclav Kotesovec_, May 23 2021
%t A344525 a[n_] := Sum[EulerPhi[k] * Quotient[n, k]^n, {k, 1, n}]; Array[a, 20] (* _Amiram Eldar_, May 22 2021 *)
%o A344525 (PARI) a(n) = sum(k=1, n, eulerphi(k)*(n\k)^n);
%o A344525 (Python)
%o A344525 from sympy import totient
%o A344525 def A344525(n): return sum(totient(k)*(n//k)**n for k in range(1,n+1)) # _Chai Wah Wu_, Aug 05 2024
%Y A344525 Main diagonal of A344479.
%Y A344525 Cf. A018806, A344140, A344522, A344523, A344524.
%K A344525 nonn
%O A344525 1,2
%A A344525 _Seiichi Manyama_, May 22 2021