G.f.: Sum_{n>=0} x^n*((1+x)^n + i)^n / (1 + i*x*(1+x)^n)^(n+1), where i^2 = -1.
A323681
G.f.: Sum_{n>=0} x^n*((1+x)^n + i)^n / (1 + i*x*(1+x)^n)^(n+1), where i^2 = -1.
Terms
- a(0) =1a(1) =1a(2) =2a(3) =7a(4) =22a(5) =87a(6) =377a(7) =1771a(8) =9026a(9) =49199a(10) =284983a(11) =1745336a(12) =11246563a(13) =75956728a(14) =535909242a(15) =3938660615a(16) =30078439304a(17) =238154159543
External references
- oeis: A323681