A024503 a(n) = floor(binomial(2*n,n)/3^n).

1, 0, 0, 0, 0, 1, 1, 1, 1, 2, 3, 3, 5, 6, 8, 10, 13, 18, 23, 30, 39, 51, 67, 87, 114, 149, 195, 255, 334, 438, 574, 753, 988, 1298, 1706, 2242, 2948, 3877, 5102, 6716, 8842, 11646, 15343, 20220, 26654, 35144, 46349, 61142, 80673, 106467, 140537, 185545, 245015

Offset

0,10

Links

Table of n, a(n) for n=0..52.

Formula

a(n) ~ (4/3)^n / sqrt(Pi*n). - Amiram Eldar, Sep 05 2025

Mathematica

a[n_] := Floor[Binomial[2*n, n] / 3^n]; Array[a, 50, 0] (* Amiram Eldar, Sep 05 2025 *)

Crossrefs

Sequence in context: A039852 A241068 A035938 * A321286 A385352 A061790

Adjacent sequences: A024500 A024501 A024502 * A024504 A024505 A024506

Keyword

nonn

Author

Clark Kimberling

Extensions

More terms from Alois P. Heinz, Jun 23 2018

Status

approved