Second column of triangle A075504.

A076008

Second column of triangle A075504.

Terms

    a(0) =1a(1) =27a(2) =567a(3) =10935a(4) =203391a(5) =3720087a(6) =67493007a(7) =1219657095a(8) =21996874431a(9) =396331160247

External references