OFFSET
1,2
COMMENTS
Start with two bins, one empty and the other containing 2n balls, n >= 1. Each turn, randomly select a ball and move it from the bin it is in to the other bin. Continue until both bins contain the same number of balls. The numbers in this sequence are the denominators of the rational expressions for the expected number of moves required to end up with the same number of balls in each bin.
PROG
(Maxima)
E(n) := (
block (
[T, P, S, i, t],
T[0] : 1,
T[1] : 1,
for i : 2 thru n do (
T[i] : T[i-1] - (n+i)*(n-i+1)*T[i-2]/(4*n^2)),
P[n] : 1,
for i : n - 1 step -1 thru 1 do (
P[i] : (n+i+1)*P[i+1]/(2*n)),
S : 0,
for i : 1 thru n do (
S : S + P[i]*T[i-1]/T[n]),
disp(S)
)
)$
CROSSREFS
KEYWORD
nonn,frac
AUTHOR
Aaron Clark and Stephen Gueble, Apr 19 2014
STATUS
approved