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 A180173 #5 Aug 02 2019 21:19:05
%S A180173 1,1,3,1,1,1,1,1,3,1,1,1,13,1,15,1,1,1,1,1,1,11,1,3,5,1,1,7,1,3,1,1,3,
%T A180173 1,7,1,1,1,3,1,1,1,1,1,15,1,1,1,1,1,3,1,1,3,5,1,3,1,1,3,1,1,1,1,1,3,1,
%U A180173 1,69,1,1,3,73,1,1,1,1,1,1,1,3,1,1,1,1,1,3,1,1,1,1,1,1,1,1,3,1,1,1,1,1,3
%N A180173 a(n) = gcd(prime(n)-2, n).
%t A180173 Table[GCD[n,Prime[n]-2],{n,200}]
%Y A180173 Cf. A084309, A084310, A180172.
%K A180173 nonn
%O A180173 1,3
%A A180173 _Zak Seidov_, Aug 15 2010