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 A366760 #12 Oct 21 2023 16:01:12
%S A366760 1,1,2,6,20,110,612,4970,39600,337680,3298900,39916800,442155168,
%T A366760 6151996372,83387930692,1282826630160,19089488332800,355148307803520,
%U A366760 5427568925856000,119931789135468100,2432901890279317572,49902667163053013232,1073067539495604750240
%N A366760 a(n) = phi(n!+1), where phi is Euler's totient function (A000010).
%F A366760 a(n) = A000010(A038507(n)).
%t A366760 EulerPhi[Range[0,25]!+1] (* _Paolo Xausa_, Oct 21 2023 *)
%o A366760 (PARI) {a(n) = eulerphi(n!+1)}
%o A366760 (Python)
%o A366760 from math import factorial
%o A366760 from sympy import totient
%o A366760 def A366760(n): return totient(factorial(n)+1) # _Chai Wah Wu_, Oct 20 2023
%Y A366760 Cf. A038507, A000010, A048855, A366759.
%K A366760 nonn
%O A366760 0,3
%A A366760 _Sean A. Irvine_, Oct 20 2023