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 A328878 #10 Nov 26 2024 15:46:46
%S A328878 1,3,5,3,11,15,17,3,5,33,31,15,41,51,55,3,59,15,67,33,85,93,83,15,11,
%T A328878 123,5,51,109,165,127,3,155,177,187,15,157,201,205,33,179,255,191,93,
%U A328878 55,249,211,15,17,33,295,123,241,15,341,51,335,327,277,165,283,381,85,3,451
%N A328878 If n = Product (p_j^k_j) then a(n) = Product (prime(p_j)).
%H A328878 Alois P. Heinz, <a href="/A328878/b328878.txt">Table of n, a(n) for n = 1..10000</a>
%H A328878 <a href="/index/Pri#prime_indices">Index entries for sequences computed from indices in prime factorization</a>
%e A328878 a(54) = 15 because 54 = 2 * 3^3 = prime(1) * prime(2)^3 and prime(prime(1)) * prime(prime(2)) = 3 * 5 = 15.
%p A328878 a:= n-> mul(ithprime(i[1]), i=ifactors(n)[2]):
%p A328878 seq(a(n), n=1..65); # _Alois P. Heinz_, Nov 26 2024
%t A328878 a[n_] := Times @@ (Prime[#[[1]]] & /@ FactorInteger[n]); Table[a[n], {n, 1, 65}]
%o A328878 (PARI) a(n)={my(f=factor(n)[,1]); prod(i=1, #f, prime(f[i]))} \\ _Andrew Howroyd_, Oct 29 2019
%Y A328878 Cf. A006450, A007947, A064988, A156061, A181819, A321874.
%K A328878 nonn,mult
%O A328878 1,2
%A A328878 _Ilya Gutkovskiy_, Oct 29 2019