A366368 - OEIS

%I #14 Oct 09 2023 09:25:24

%S 1,1,2,6,24,120,360,2520,10080,30240,151200,1663200,1663200,21621600,

%T 151351200,151351200,605404800,10291881600,30875644800,586637251200,

%U 586637251200,586637251200,6453009763200,148419224553600,148419224553600,742096122768000,9647249595984000,28941748787952000

%N a(n) = LCM of pairwise products of distinct integers from {1,2,...,n}.

%C A003418(n) divides a(n), which in turn divides A003418(n)^2. Furthermore, A003418(n)^2 / a(n) = A366369(n) is squarefree.

%F a(n) = A003418(n)^2 / A366369(n).

%F a(n) = A003418(n) * A139550(n) = A003418(n) * A003418(floor(n/2)).

%o (PARI) a366368(n) = my(k,r); r=1; forprime(p=2,n, k=logint(n,p); r *= p^(2*k - (n<2*p^k)) ); r;

%Y Cf. A003418, A139550, A366369.

%K nonn

%O 0,3

%A _Max Alekseyev_, Oct 08 2023