Essentially A053506 but with leading 0 (instead of 1) and offset 0.

A055861

Essentially A053506 but with leading 0 (instead of 1) and offset 0.

Terms

    a(0) =0a(1) =0a(2) =6a(3) =48a(4) =500a(5) =6480a(6) =100842a(7) =1835008a(8) =38263752a(9) =900000000a(10) =23579476910a(11) =681091006464

External references