OFFSET
4,3
COMMENTS
Old name was: Hit polynomials.
REFERENCES
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
LINKS
Alois P. Heinz, Table of n, a(n) for n = 4..400
Earl Glen Whitehead, Jr., Four-discordant permutations, J. Austral. Math. Soc. Ser. A 28 (1979), no. 3, 369-377.
D. Zeilberger, Automatic Enumeration of Generalized Menage Numbers, arXiv preprint arXiv:1401.1089 [math.CO], 2014. [This is a different document from the one with the same title on Doron Zeilberger's web site]
D. Zeilberger, Automatic Enumeration of Generalized Ménage Numbers
D. Zeilberger, Automatic Enumeration of Generalized Ménage Numbers [Local copy, pdf file only, no active links]
FORMULA
a(n) ~ exp(-4) * n!. - Vaclav Kotesovec, Sep 13 2014
MATHEMATICA
(* Very slow *) b[n_, n0_] := Permanent[Table[If[(0 <= j-i && j-i < n-n0) || j-i < -n0, 1, 0], {i, 1, n}, {j, 1, n}]];
a[n_] := b[n, 4];
Table[an = a[n]; Print["a(", n, ") = ", an]; an, {n, 4, 24}] (* Jean-François Alcover, Oct 08 2017 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
EXTENSIONS
More terms from Vladeta Jovovic, Oct 02 2003
Name changed by Andrew Howroyd, Sep 19 2017
STATUS
approved