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 A119619 #21 Sep 08 2022 08:45:25
%S A119619 1,1,2,3,24,10,720,315,4480,4536,3628800,11550,479001600,13899600,
%T A119619 43051008,638512875,20922789888000,1905904000,6402373705728000,
%U A119619 118794043368,68108451840000,4535772564960000,1124000727777607680000
%N A119619 a(n) = Product_{i=1..n} i / gcd(i,n).
%C A119619 If p is prime, then a(p) = (p-1)!. - _Stefan Steinerberger_, Jun 08 2006
%F A119619 a(n) = Product_{d|n} pxi(d), where pxi(m) = is the product of totatives of m (A001783). - _Jaroslav Krizek_, Dec 28 2016
%F A119619 a(n) = A000142(n)/A067911(n). - _Ridouane Oudra_, Nov 20 2021
%p A119619 a:=n->mul(numer (k/n), k=1..n): seq(a(n), n=1..23); # _Zerinvary Lajos_, Apr 26 2008
%t A119619 a[n_] := Product[i/GCD[i, n], {i, 1, n}]; Table[a[n], {n, 1, 30}] (* _Stefan Steinerberger_, Jun 08 2006 *)
%t A119619 Table[Product[Times @@ Select[Range@ d, CoprimeQ[#, d] &], {d, Divisors@ n}], {n, 23}] (* _Michael De Vlieger_, Dec 28 2016 *)
%o A119619 (PARI) a(n) = prod(i=1,n,i/gcd(i,n))
%o A119619 (Magma) [&*[&*[h: h in [1..d] | GCD(h,d) eq 1]: d in Divisors(n)]: n in [1..100]]; // _Jaroslav Krizek_, Dec 28 2016
%Y A119619 Cf. A067911.
%Y A119619 Cf. A000142, A067911.
%K A119619 nonn
%O A119619 1,3
%A A119619 _Martin Fuller_, Jun 06 2006
%E A119619 More terms from _Stefan Steinerberger_, Jun 08 2006