a(0) = 1; a(n) = 3 * Sum_{k=0..floor((n-1)/2)} binomial(n-1,2*k) * a(n-2*k-1).
A352280
a(0) = 1; a(n) = 3 * Sum_{k=0..floor((n-1)/2)} binomial(n-1,2*k) * a(n-2*k-1).
Terms
- a(0) =1a(1) =3a(2) =9a(3) =30a(4) =117a(5) =516a(6) =2493a(7) =13152a(8) =75177a(9) =460272a(10) =3003921a(11) =20806176a(12) =152114013a(13) =1169842368a(14) =9435180357a(15) =79553524224a(16) =699531782481
External references
- oeis: A352280