Main diagonal of rectangular table A121426.

A121427

Main diagonal of rectangular table A121426.

Terms

    a(0) =1a(1) =2a(2) =15a(3) =178a(4) =2820a(5) =55410a(6) =1294776a(7) =35003430a(8) =1073540871a(9) =36805249870

External references