OFFSET
0,2
COMMENTS
From N. J. A. Sloane, Jul 14 2009: (Start)
The following remarks and formulas are basically copied from the Apagodu-Zeilberger reference, where this sequence appears as an example.
These are the (old-time) basketball numbers, giving the number of ways a basketball game that ended with the score n : n can proceed. Recall that in the old days (before 1961), an atom of basketball-scoring could be only of one or two points.
Equivalently, this number is the number of ways of walking, in the square lattice, from (0; 0) to (n; n) using the atomic steps {(1; 0); (2; 0); (0; 1); (0; 2)}.
It satisfies the third-order linear recurrence:
(16/5)(2n + 3)(11n + 26)(1 + n)/((n + 3)(2 + n)(11n + 15))a(n)
-(4/5)(121n^3 + 649n^2 + 1135n + 646)/((n + 3)(2 + n)(11n + 15))a(1 + n)
-(2/5)(176n^2 + 680n + 605)/((11n + 15)(n + 3))a(2 + n) + a(n + 3) = 0 ;
subject to the initial conditions: a(0) = 1; a(1) = 2; a(2) = 14 :
Asymptotics: (0.37305616)(4 + 2*sqrt(3))^n*n^(-1/2)(1 + (67/1452)*sqrt(3) -(119/484))/n +((6253/117128) -(7163/234256)sqrt(3))/n^2 +(-(32645/ 15460896) sqrt(3) +(129625/10307264))/n^3).
(End)
In closed form, multiplicative constant is sqrt((15+8*sqrt(3))/(66*Pi)) = 0.37305616313160230... - Vaclav Kotesovec, Oct 24 2012
Diagonal of rational function 1/(1 - (x + y + x^2 + y^2)). - Gheorghe Coserea, Aug 06 2018
LINKS
Reinhard Zumkeller, Table of n, a(n) for n = 0..1000
Moa Apagodu and Doron Zeilberger, FIVE Applications of Wilf-Zeilberger Theory to Enumeration and Probability; Local copy [Pdf file only, no active links]
FORMULA
G.f.: ((3-4*x+2*(4*x^2-8*x+1)^(1/2))/((8*x+5)*(4*x^2-8*x+1)))^(1/2). - Mark van Hoeij, Oct 30 2011
MATHEMATICA
CoefficientList[Series[((3-4*x+2*(4*x^2-8*x+1)^(1/2))/((8*x+5)*(4*x^2-8*x+1)))^(1/2), {x, 0, 20}], x] (* Vaclav Kotesovec, Oct 24 2012 *)
PROG
(PARI) /* same as in A092566 but use */
steps=[[1, 0], [2, 0], [0, 1], [0, 2]];
/* Joerg Arndt, Jun 30 2011 */
(Haskell)
a036692 n = a036355 (2 * n) n -- Reinhard Zumkeller, Apr 24 2013
CROSSREFS
KEYWORD
nonn
AUTHOR
EXTENSIONS
Extended by Christian G. Bower, Nov 18 2003
STATUS
approved