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 A064935 #23 Feb 14 2025 03:36:05 %S A064935 4,64,376,1188,1468,25804,58588,134944,137344,170584,272608,285388, %T A064935 420208,538732,592408,618448,680704,778804,1163064,1520440,1700944, %U A064935 2099200,2831008,4020028,4174168,4516108,5059888,5215768,5447272 %N A064935 Numbers k such that (k+3)^(k+2) mod (k+1) = k. %C A064935 From _Robert Israel_, Feb 13 2025: (Start) %C A064935 Numbers k such that 2^(k+2) == -1 (mod k+1). %C A064935 All terms are divisible by 4. %C A064935 The only term k where k+1 is prime is 4. %C A064935 (End) %H A064935 Robert Israel, <a href="/A064935/b064935.txt">Table of n, a(n) for n = 1..350</a> %e A064935 (4+3)^(4+2) mod (4+1) = 7^6 mod 5 = 117649 mod 5 = 4, so 4 is a term. %p A064935 filter:= proc(k) 2 &^(k+2) mod (k+1) = k end proc: %p A064935 select(filter, [seq(i,i=4..10^7,4)]); # _Robert Israel_, Feb 13 2025 %o A064935 (PARI) isok(k) = Mod(k+3, k+1)^(k+2) == k; \\ _Michel Marcus_, Jul 12 2021 %Y A064935 Equals A055685(n+1) - 2. %K A064935 nonn %O A064935 1,1 %A A064935 Jonathan Ayres (jonathan.ayres(AT)btinternet.com), Oct 26 2001