G.f.: A(x) = Sum_{n>=0} (1 + x)^(n^2+n) / 2^(n+1).
A173218
G.f.: A(x) = Sum_{n>=0} (1 + x)^(n^2+n) / 2^(n+1).
Terms
- a(0) =1a(1) =4a(2) =50a(3) =1040a(4) =30300a(5) =1135080a(6) =51972668a(7) =2812429632a(8) =175606496520
External references
- oeis: A173218