a(n) = n*(n-1)/2 * 2^(n*(n-1)/2).A103904a(n) = n*(n-1)/2 * 2^(n*(n-1)/2).Terms a(0) =0a(1) =2a(2) =24a(3) =384a(4) =10240a(5) =491520a(6) =44040192a(7) =7516192768External referencesoeis: A103904