a(0) = 1; a(n) = Sum_{k=0..floor((n-1)/3)} binomial(n-1,3*k) * a(k) * a(n-3*k-1).
A351968
a(0) = 1; a(n) = Sum_{k=0..floor((n-1)/3)} binomial(n-1,3*k) * a(k) * a(n-3*k-1).
Terms
- a(0) =1a(1) =1a(2) =1a(3) =1a(4) =2a(5) =6a(6) =16a(7) =37a(8) =114a(9) =478a(10) =1907a(11) =6777a(12) =28414a(13) =148580a(14) =758930a(15) =3580294a(16) =18982050a(17) =117888762a(18) =720679726a(19) =4193516446a(20) =26798335830a(21) =191775198574
External references
- oeis: A351968