A337292 a(n) = 4*binomial(5*n,n)/(5*n-1).

5, 20, 130, 1020, 8855, 81900, 791120, 7887660, 80560285, 838553320, 8863227100, 94871786100, 1026317094705, 11203116342560, 123243929011680, 1364973221797900, 15207477517956825, 170321264840835900, 1916512328325665070, 21655893753689280120

Offset

1,1

Comments

a(n) is the number of lattice paths from (0,0) to (4n,n) using only the steps (1,0) and (0,1) and whose only lattice points on the line y = x/4 are the path's endpoints.

Links

Table of n, a(n) for n=1..20.

Formula

a(n) = 5*A118971(n-1).

G.f.: 5*x*F(x)^4 where F(x) = 1 + x*F(x)^5 is the g.f. of A002294.

Mathematica

Array[4 Binomial[5 #, #]/(5 # - 1) &, 20] (* Michael De Vlieger, Aug 21 2020 *)

Prog

(PARI) a(n) = {4*binomial(5*n, n)/(5*n-1)} \\ Andrew Howroyd, Aug 21 2020

Crossrefs

Cf. A002294, A118971, A337291.

Sequence in context: A110373 A081067 A318250 * A024066 A009569 A061964

Adjacent sequences: A337289 A337290 A337291 * A337293 A337294 A337295

Keyword

nonn,easy

Author

Lucas A. Brown, Aug 21 2020

Status

approved