A024501 a(n) = floor(C(4n,2n)/C(4n,n)).

1, 1, 2, 4, 7, 11, 20, 33, 57, 96, 162, 274, 462, 780, 1317, 2223, 3751, 6329, 10680, 18021, 30409, 51312, 86584, 146103, 246538, 416013, 701993, 1184566, 1998882, 3372999, 5691754, 9604549, 16207222, 27348969, 46150243, 77876717, 131414064

Offset

0,3

Links

Table of n, a(n) for n=0..36.

Formula

a(n) = floor(C(4n,2n)/C(4n/n)) = floor(C(3n,n)/C(2n,n)). - Clark Kimberling, Dec 23 2022

Mathematica

Floor[Table[Binomial[4n, 2n]/Binomial[4n, n], {n, 0, 40}]] (* Clark Kimberling, Dec 22 2022 *)

Crossrefs

Cf. A000984.

Sequence in context: A364590 A151992 A242362 * A160393 A018173 A288380

Adjacent sequences: A024498 A024499 A024500 * A024502 A024503 A024504

Keyword

nonn

Author

Clark Kimberling

Extensions

More terms from James A. Sellers, Feb 06 2000

Status

approved