a(n) = n! * Sum_{k=0..floor(n/2)} (k/2)^k / (k! * (n-2*k)!).

A362350

a(n) = n! * Sum_{k=0..floor(n/2)} (k/2)^k / (k! * (n-2*k)!).

Terms

    a(0) =1a(1) =1a(2) =2a(3) =4a(4) =19a(5) =71a(6) =601a(7) =3277a(8) =39089a(9) =277489a(10) =4250341a(11) =37110701a(12) =693581197a(13) =7184750509a(14) =158461520309

External references