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 A177164 #9 Jun 06 2021 09:02:24
%S A177164 1,5,9972894583,
%T A177164 449853889404077636694265177903207995382439448590987815041588427345865911961016023550064137351211162870609
%N A177164 a(n) = (n^r - 1)/r^2, where r = (n^(n-1) - 1)/(n-1).
%C A177164 The next term has 1204 digits.
%C A177164 r = (n^(n-1) - 1)/(n-1) = A060072(n) is the (n-1)-digit repunit in base n.
%C A177164 r^2 divides n^r - 1 for all bases n > 1.
%F A177164 a(n) = (n^((n^(n-1) - 1)/(n-1)) - 1)/((n^(n-1) - 1)/(n-1))^2.
%F A177164 a(n) = (n^A060072(n) - 1)/A060072(n)^2.
%e A177164 a(10) = (10^111111111 - 1)/111111111^2.
%t A177164 Table[(n^((n^(n - 1) - 1)/(n - 1)) - 1)/((n^(n - 1) - 1)/(n - 1))^2, {n, 2, 6}]
%Y A177164 Cf. A060072, A127100, A127101, A127102, A127103, A127104, A127105, A127106, A127107, A127092.
%K A177164 nonn
%O A177164 2,2
%A A177164 _Alexander Adamchuk_, May 04 2010