a(n) = Product_{1 <= j <= k <= n} (k^2 + j^2).A293290a(n) = Product_{1 <= j <= k <= n} (k^2 + j^2).Terms a(0) =1a(1) =2a(2) =80a(3) =187200a(4) =50918400000External referencesoeis: A293290