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 A377678 #10 Nov 04 2024 01:36:38 %S A377678 1,8,72,768,12400,217728,7112448,94371840,2594586816,69139840000, %T A377678 2584376931840,58779453358080,4367959006806720,100089965305451520, %U A377678 3251736576000000000,200445251536048619520,12343971160877345120064,422076038504126628593664 %N A377678 a(n) = phi(n^n - n) where phi is the Euler totient function. %H A377678 Amiram Eldar, <a href="/A377678/b377678.txt">Table of n, a(n) for n = 2..115</a> %F A377678 a(n) = A000010(A061190(n)). %t A377678 a[n_] := EulerPhi[n^n - n]; Array[a, 20, 2] (* _Amiram Eldar_, Nov 04 2024 *) %o A377678 (PARI) a(n) = eulerphi(n^n-n); %Y A377678 Cf. A000010, A061190, A366821, A372229, A372599, A377674, A377675, A377676, A377677. %K A377678 nonn %O A377678 2,2 %A A377678 _Sean A. Irvine_, Nov 03 2024