OFFSET
0,3
REFERENCES
A. P. Heinz (1990). Analyse der Grenzen und Möglichkeiten schneller Tableauoptimierung. PhD Thesis, Albert-Ludwigs-Universität Freiburg, Freiburg i. Br., Germany.
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..200
FORMULA
EXAMPLE
a(2) = 4 because there are 4 relations of the given kind for 2 elements: 1R1, 2R2; 1R1, 2R2, 1R2; 1R1, 2R2, 2R1; 1R1, 2R2, 1R2, 2R1.
MAPLE
df:= proc(n) option remember; `if`(n<=1, 1, n*df(n-2)) end: u:= proc(n) add(binomial(n, i) *(n-i)^i, i=0..n) end: a:= proc(n) add(binomial(n, i+i) *df(i+i-1) *u(n-i-i), i=0..floor(n/2)) end: seq(a(n), n=0..50);
MATHEMATICA
a[n_] := SeriesCoefficient[Exp[x*Exp[x] + x^2/2], {x, 0, n}]*n!; Table[a[n], {n, 0, 50}] (* Jean-François Alcover, Feb 04 2014 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Dec 05 2007
STATUS
approved