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 A066606 #20 Dec 07 2024 14:55:48
%S A066606 0,0,8,0,7,28,30,0,26,24,112,64,80,116,143,0,155,28,116,176,197,444,
%T A066606 255,64,57,316,80,128,60,424,374,0,602,616,18,784,76,460,944,576,207,
%U A066606 1324,303,1600,782,1016,1929,1792,2382,124,1844,2512,1009,568,1693,704
%N A066606 a(n) = 2^n mod n^2.
%H A066606 Alois P. Heinz, <a href="/A066606/b066606.txt">Table of n, a(n) for n = 1..10000</a> (first 1000 terms from Harry J. Smith)
%e A066606 a(7) = 30 as 2^7 = 128 = (7^2)*2 + 30.
%p A066606 a:= n-> 2&^n mod (n^2):
%p A066606 seq(a(n), n=1..100); # _Alois P. Heinz_, Jul 04 2017
%t A066606 Table[PowerMod[2,n,n^2],{n,60}] (* _Harvey P. Dale_, Dec 08 2015 *)
%o A066606 (PARI) a(n) = { lift(Mod(2, n^2)^n) } \\ _Harry J. Smith_, Mar 10 2010
%K A066606 easy,nonn
%O A066606 1,3
%A A066606 _Amarnath Murthy_, Dec 22 2001
%E A066606 More terms from _Floor van Lamoen_ and _Robert G. Wilson v_, Dec 23 2001