G.f.: Sum_{n>=0} (1+x)^n * Product_{k=1..n} ((1+x)^k - 1).
A207556
G.f.: Sum_{n>=0} (1+x)^n * Product_{k=1..n} ((1+x)^k - 1).
Terms
- a(0) =1a(1) =1a(2) =3a(3) =11a(4) =55a(5) =339a(6) =2499a(7) =21433a(8) =209717a(9) =2305719a(10) =28141925a(11) =377579731a(12) =5523750291a(13) =87508680045
External references
- oeis: A207556