OFFSET
0,3
COMMENTS
a(n) is also number of ways to place n nonattacking pieces rook + leaper[3,3] on an n X n chessboard.
LINKS
Vaclav Kotesovec, Table of n, a(n) for n = 0..30
Vaclav Kotesovec, Non-attacking chess pieces, Sixth edition, p. 633, Feb 02 2013.
Vaclav Kotesovec, Mathematica program for this sequence
Roberto Tauraso, The Dinner Table Problem: The Rectangular Case, INTEGERS: Electronic Journal of Combinatorial Number Theory, Vol. 6 (2006), #A11.
FORMULA
Formula given in Tauraso reference.
Asymptotic (R. Tauraso 2006, quadratic term V. Kotesovec 2011): a(n)/n! ~ (1 + 8/n + 30/n^2)/e^2.
CROSSREFS
KEYWORD
nonn,hard
AUTHOR
James A. Sellers, Apr 27 2006
EXTENSIONS
Terms a(17)-a(28) from Vaclav Kotesovec, Apr 19 2011
Terms a(29)-a(30) from Vaclav Kotesovec, Apr 20 2012
a(0)=1 prepended by Alois P. Heinz, Feb 05 2023
STATUS
approved