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 A387400 #11 Sep 04 2025 17:30:19 %S A387400 1,1,1,2,1,4,2,3,3,5,1,7,2,6,8,7,3,8,2,9,7,5,2,12,5,6,9,11,2,15,3,15, %T A387400 8,7,9,13,2,8,8,17,5,18,3,11,14,7,2,24,9,13,10,14,1,20,11,17,9,8,1,27, %U A387400 4,9,19,31,15,18,3,12,10,22,2,23,5,9,17,13,16,23,4,33,26,10,1,31,13,9,12,20,4,27 %N A387400 Number of nonnegative s < n such that s^s == s^n (mod n). %o A387400 (Magma) [#[s: s in [0..n-1] | Modexp(s,s,n) eq Modexp(s,n,n)]: n in [1..90]]; %o A387400 (PARI) a(n) = sum(s=0, n-1, Mod(s,n)^n == Mod(s, n)^s); \\ _Michel Marcus_, Aug 30 2025 %Y A387400 Cf. A065295, A182816. %K A387400 nonn,new %O A387400 1,4 %A A387400 _Juri-Stepan Gerasimov_, Aug 28 2025