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 A062175 #12 Jun 09 2022 19:42:48
%S A062175 0,0,1,0,1,4,1,0,7,4,1,4,1,4,1,0,1,16,1,4,16,4,1,16,6,4,7,8,1,4,1,0,
%T A062175 16,4,11,16,1,4,16,24,1,16,1,20,16,4,1,16,29,44,16,12,1,34,36,32,16,4,
%U A062175 1,4,1,4,16,0,61,34,1,64,16,64,1,16,1,4,31,64,4,10,1,64,61,4,1,16,1,4,16
%N A062175 a(n) = 4^(n-1) mod n.
%H A062175 Harry J. Smith, <a href="/A062175/b062175.txt">Table of n, a(n) for n = 1..1000</a>
%H A062175 <a href="/index/Ps#pseudoprimes">Index entries for sequences related to pseudoprimes</a>
%t A062175 Table[PowerMod[4,n-1,n],{n,90}] (* _Harvey P. Dale_, Jun 09 2022 *)
%o A062175 (PARI) { for (n=1, 1000, write("b062175.txt", n, " ", 4^(n - 1)%n) ) } \\ _Harry J. Smith_, Aug 02 2009
%Y A062175 Cf. A062172.
%K A062175 nonn
%O A062175 1,6
%A A062175 _Henry Bottomley_, Jun 12 2001