Column 2 of triangle A138271; also, column 0 of matrix power A138271^3.
A138274
Column 2 of triangle A138271; also, column 0 of matrix power A138271^3.
Terms
- a(0) =1a(1) =3a(2) =18a(3) =156a(4) =1714a(5) =22368a(6) =333910a(7) =5566728a(8) =101955050a(9) =2027241660a(10) =43372029642a(11) =991507256804
External references
- oeis: A138274