M*(M-1), where M is Mersenne prime A000668(n).

A139223

M*(M-1), where M is Mersenne prime A000668(n).

Terms

    a(0) =6a(1) =42a(2) =930a(3) =16002a(4) =67084290a(5) =17179475970a(6) =274876334082

External references