OFFSET
0,4
COMMENTS
Related to the Catalan numbers (which count the ways of storing an arbitrary number of bottles above n bottles at ground level).
Related to fountains of n coins (A005169). [Joerg Arndt, Mar 18 2011]
REFERENCES
R. P. Stanley, Enumerative Combinatorics (Volume 2); see Exercise 6.19(hhh).
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..600
Andrew M. Odlyzko and Herbert S. Wilf, The editor's corner: n coins in a fountain, Amer. Math. Monthly, 95 (1988), 840-843.
FORMULA
Coefficient of w^(2*n+1)*z^(n+1) in the formal power series G(w, z) defined by G(w, z)=1+w*z*G(w, w*z).
a(n) = A047998(2n+1,n+1). - Alois P. Heinz, Jun 24 2015
a(n) ~ c * d^n / sqrt(n), where d = 2.8566122635122125634030051... and c = 0.19212135026441477122126... - Vaclav Kotesovec, Jul 17 2019
EXAMPLE
a(4) = 7: the seven possibilities are:
..............0.............0.........0...............0.........0............0
.0.0.0.0.....0.0.0.......0.0.0.......0.0...0.....0...0.0.......0.0.0......0.0.0
0.0.0.0.0.,.0.0.0.0.0.,.0.0.0.0.0.,.0.0.0.0.0.,.0.0.0.0.0.,.0.0.0.0.0,.0.0.0.0.0
MATHEMATICA
terms = 31; initialMax = 5; Clear[g]; g[max_] := g[max] = (Print["max = ", max]; f = 1/Fold[1 - y*x^#2/#1&, 1, Range[max] // Reverse]; b[n_, k_] := SeriesCoefficient[f, {x, 0, n}, {y, 0, k}]; b[0, 0] = 1; Clear[a]; a[n_] := a[n] = b[2n+1, n+1]; Array[a, terms, 0]); g[max = initialMax]; g[max = max+1]; While[g[max] != g[max-1], max = max+1]; A058300 = g[max] (* Jean-François Alcover, Oct 05 2017, after Alois P. Heinz's formula *)
CROSSREFS
KEYWORD
easy,nonn,nice
AUTHOR
Roland Bacher, Dec 08 2000
EXTENSIONS
More terms from Alois P. Heinz, Jun 24 2015
STATUS
approved