G.f.: A(x) = Sum_{n>=0} (1 + x)^(n(n+1)/2) / 2^(n+1).
A173219
G.f.: A(x) = Sum_{n>=0} (1 + x)^(n(n+1)/2) / 2^(n+1).
Terms
- a(0) =1a(1) =2a(2) =12a(3) =124a(4) =1800a(5) =33648a(6) =769336a(7) =20796960a(8) =648841680a(9) =22945907520a(10) =907036108432
External references
- oeis: A173219