G.f.: Sum_{n>=0} x^n / (1-x)^(2*n+1) * [ Sum_{k=0..n} C(n,k)^2*x^k ]^2.
A227845
G.f.: Sum_{n>=0} x^n / (1-x)^(2*n+1) * [ Sum_{k=0..n} C(n,k)^2*x^k ]^2.
Terms
- a(0) =1a(1) =2a(2) =7a(3) =28a(4) =125a(5) =590a(6) =2891a(7) =14536a(8) =74497a(9) =387450a(10) =2038743a(11) =10830148a(12) =57986773a(13) =312542678a(14) =1694166275a(15) =9228580464a(16) =50486521785a(17) =277239830210
External references
- oeis: A227845