G.f.: Sum_{n>=0} x^n * ((1+x)^n + 2*i)^n / (1 + 2*i*x*(1+x)^n)^(n+1), where i^2 = -1.
A323684
G.f.: Sum_{n>=0} x^n * ((1+x)^n + 2*i)^n / (1 + 2*i*x*(1+x)^n)^(n+1), where i^2 = -1.
Terms
- a(0) =1a(1) =1a(2) =2a(3) =13a(4) =40a(5) =177a(6) =959a(7) =4927a(8) =28118a(9) =173747a(10) =1116769a(11) =7572422a(12) =53958439a(13) =400843780a(14) =3100289406a(15) =24912295541a(16) =207402869744
External references
- oeis: A323684