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 A338364 #20 Jan 03 2021 00:31:43
%S A338364 1,1,1,2,4,16,64,512,3072,30720,368640,2949120,35389440,566231040,
%T A338364 6794772480,149484994560,3587639869440,100453916344320,
%U A338364 1607262661509120,32145253230182400,771486077524377600,18515665860585062400,444375980654041497600,17775039226161659904000
%N A338364 a(n) = Product_{k=1..n} phi(prime(k)-1).
%e A338364 a(5) = phi(1)*phi(2)*phi(4)*phi(6)*phi(10) = 1*1*2*2*4 = 16.
%p A338364 with(NumberTheory);
%p A338364 f:=n->mul(phi(ithprime(k)-1),k=1..n);
%p A338364 [seq(f(n),n=1..32)];
%o A338364 (PARI) a(n) = prod(k=1, n, eulerphi(prime(k)-1)); \\ _Michel Marcus_, Nov 04 2020
%Y A338364 Cf. A000010, A008330, A002110.
%K A338364 nonn
%O A338364 0,4
%A A338364 _Marc LeBrun_ and _N. J. A. Sloane_, Nov 04 2020