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 A321613 #20 Jul 24 2019 08:49:19
%S A321613 1,1,2,6,24,48,288,2016,16128,64512,645120,3870720,46448640,278691840,
%T A321613 2229534720,33443020800,535088332800,4280706662400,77052719923200,
%U A321613 924632639078400,11095591668940800,110955916689408000,2441030167166976000,34174422340337664000
%N A321613 Partial products of the unitary totient function (A047994): a(n) = Product_{k=1..n} uphi(k).
%C A321613 a(n) is also the determinant of the symmetric n X n matrix M defined by M(i,j) = ugcd(i,j) for 1 <= i,j <= n, where ugcd(i,j) in the greatest common unitary divisor of i and j (A165430).
%C A321613 The unitary version of A001088.
%H A321613 Amiram Eldar, <a href="/A321613/b321613.txt">Table of n, a(n) for n = 1..481</a>
%H A321613 H. Jager, <a href="https://core.ac.uk/download/pdf/81954577.pdf">The unitary analogues of some identities for certain arithmetical functions</a>, Nederl. Akad. Wetensch. Proc. Ser. A, Vol. 64 (1961), pp. 508-515.
%e A321613 a(4) = uphi(1) * uphi(2) * uphi(3) * uphi(4) = 1 * 1 * 2 * 3 = 6.
%t A321613 uphi[1] = 1; uphi[n_] := Times @@ (-1 + Power @@@ FactorInteger[n]); FoldList[ Times, uphi /@ Range[50]]
%o A321613 (PARI) uphi(n) = my(f=factor(n)~); prod(i=1, #f, f[1, i]^f[2, i]-1); \\ A047994
%o A321613 a(n) = prod(k=1, n, uphi(k)); \\ _Michel Marcus_, Dec 19 2018
%Y A321613 Cf. A001088, A047994, A165430, A177754.
%K A321613 nonn
%O A321613 1,3
%A A321613 _Amiram Eldar_, Dec 19 2018