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 A058665 #28 Dec 12 2021 20:07:42
%S A058665 2,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,3,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
%T A058665 1,1,1,1,5,1,1,1,1,3,1,1,1,1,1,3,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,3,
%U A058665 5,1,1,1,1,1,1,1,1,1,1,3,1,1,1,5,1,1,1,1,1,1,1,3,1,1,1,1,1,1,1,1,1,1,1,7,1
%N A058665 a(n) = gcd(n+1, n-phi(n)).
%C A058665 a(n) = 1 for most n. True for all primes and other integers.
%H A058665 Antti Karttunen, <a href="/A058665/b058665.txt">Table of n, a(n) for n = 1..10000</a>
%F A058665 a(n) = gcd(n+1, cototient(n)) = gcd(n+1, A051953(n)).
%e A058665 n = 247 = 13*19, n+1 = 248 = 8*31, phi(247) = 12*18 = 216, cototient(247) = 247-216 = 31, so a(247) = gcd(248,31) = 31.
%t A058665 Table[GCD[n+1,n-EulerPhi[n]],{n,0,110}] (* _Harvey P. Dale_, Dec 24 2012 *)
%o A058665 (PARI) A058665(n) = gcd(n+1, n-eulerphi(n)); \\ _Antti Karttunen_, Jul 28 2017
%o A058665 (Python)
%o A058665 from sympy import gcd, totient
%o A058665 def a(n): return gcd(n + 1, n - totient(n))
%o A058665 print([a(n) for n in range(1, 51)]) # _Indranil Ghosh_, Jul 29 2017
%Y A058665 Cf. A000010, A051953, A009195.
%K A058665 nonn
%O A058665 1,1
%A A058665 _Labos Elemer_, Dec 28 2000
%E A058665 Offset corrected by _Antti Karttunen_, Jul 28 2017