a(0) = 1; a(n) = Sum_{k=0..floor((n-1)/4)} binomial(n-1,4*k) * a(k) * a(n-4*k-1).
A351969
a(0) = 1; a(n) = Sum_{k=0..floor((n-1)/4)} binomial(n-1,4*k) * a(k) * a(n-4*k-1).
Terms
- a(0) =1a(1) =1a(2) =1a(3) =1a(4) =1a(5) =2a(6) =7a(7) =22a(8) =57a(9) =128a(10) =389a(11) =1904a(12) =9329a(13) =38040a(14) =132147a(15) =542648a(16) =3283633a(17) =20997824a(18) =114657097a(19) =536178880a(20) =2784500161a(21) =19876061313a(22) =153326461333
External references
- oeis: A351969