OFFSET
0,4
LINKS
Philippe Flajolet, A seating arrangement problem
Philippe Flajolet, A seating arrangement problem [Cached copy]
Dave Freedman and Larry Shepp, An unfriendly seating arrangement, Problem 62-3, SIAM Review, Vol. 6 (1964), 180-182.
MAPLE
g:=proc(n) local k; option remember;
if n<=0 then 1 elif n=1 then u else
expand(u/n*convert([seq(g(k-2)*g(n-k-1), k=1..n)], `+`));
fi
end:
l2:=subs(u=1, diff([seq(g(j), j=0..25)], u, u));
[seq(l2[i]*(i-1)!, i=1..26)];
MATHEMATICA
g[n_] := g[n] = Switch[n, -1|0, 1, 1, u, _, u/n Sum[g[k-2] g[n-k-1], {k, 1, n}]];
D[Table[g[j] j!, {j, 0, 25}], {u, 2}] /. u -> 1 (* Jean-François Alcover, Jul 29 2018, from Maple *)
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Mar 29 2014
STATUS
approved