Related to graded partially ordered sets.

A001829

Related to graded partially ordered sets.

Terms

    a(0) =1a(1) =6a(2) =46a(3) =450a(4) =5650a(5) =91866a(6) =1957066a(7) =55363650a(8) =2109599650a(9) =109773407466

External references