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 A126560 #16 Dec 14 2023 05:20:48
%S A126560 4,2,2,4,8,2,2,8,4,2,2,4,8,2,2,8,4,2,2,4,8,2,2,8,4,2,2,4,8,2,2,8,4,2,
%T A126560 2,4,8,2,2,8,4,2,2,4,8,2,2,8,4,2,2,4,8,2,2,8,4,2,2,4,8,2,2,8,4,2,2,4,
%U A126560 8,2,2,8,4,2,2,4,8,2,2,8,4,2,2,4,8,2,2,8,4,2,2,4,8,2,2,8,4,2,2,4,8,2,2,8
%N A126560 a(n) = gcd(4(n+1)(n+2), n(n+3)), periodic with 8-cycle 4,2,2,4,8,2,2,8.
%C A126560 a(n) = n*(3 + n)/A125650(n). Sequence is periodic with cycle 4,2,2,4,8,2,2,8.
%H A126560 Antti Karttunen, <a href="/A126560/b126560.txt">Table of n, a(n) for n = 1..8192</a>
%F A126560 a(n) = GCD[4(n+1)(n+2),n(n+3)]
%F A126560 a(n)=4+(-1+1/2*2^(1/2))*cos(Pi*n/4)-1/2*2^(1/2)*sin(Pi*n/4)+(-1/2*2^(1/2)-1)*cos(3*Pi*n/4)-1/2*2^(1/2)*sin(3*Pi*n/4)+2*cos(n*Pi/2)-2*sin(n*Pi/2) [From _Richard Choulet_, Dec 11 2008]
%t A126560 Table[GCD[m(3+m),4(1+m)(2+m)],{m,48}]
%o A126560 (PARI) A126560(n) = gcd(4*(n+1)*(n+2),n*(n+3)); \\ _Antti Karttunen_, Aug 11 2017
%Y A126560 Cf. A125650.
%K A126560 nonn
%O A126560 1,1
%A A126560 _Zak Seidov_, Mar 12 2007
%E A126560 More terms from _Antti Karttunen_, Aug 11 2017