

A189256


Number of permutations p of 1,2,...,n satisfying p(i+5)p(i)<>5 for all 1<=i<=n5.


4



1, 2, 6, 24, 120, 672, 4128, 28992, 231936, 2088960, 20434944, 221871360, 2645370624, 34344038400, 482103767040, 7269498483456, 117240911729664, 2013265377314688, 36665783917283328, 705762463906133760, 14313891805008665856
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OFFSET

1,2


COMMENTS

a(n) is also number of ways to place n nonattacking pieces rook + leaper[5,5] on an n X n chessboard.


REFERENCES

Roberto Tauraso, The Dinner Table Problem: The Rectangular Case, INTEGERS, vol. 6 (2006), paper A11.


LINKS

Vaclav Kotesovec, Table of n, a(n) for n = 1..26
V. Kotesovec, Number of ways of placing nonattacking queens, kings, bishops and knights (in English and Czech)
Vaclav Kotesovec, Mathematica program for this sequence


FORMULA

Asymptotic (R. Tauraso 2006, quadratic term V. Kotesovec 2011): a(n)/n! ~ (1 + 16/n + 110/n^2)/e^2.


CROSSREFS

Cf. A002464, A110128, A117574, A189255.
Sequence in context: A177529 A138619 A189841 * A152344 A152340 A152347
Adjacent sequences: A189253 A189254 A189255 * A189257 A189258 A189259


KEYWORD

nonn,hard


AUTHOR

Vaclav Kotesovec, Apr 19 2011


EXTENSIONS

Terms a(25)a(26) from Vaclav Kotesovec, Apr 20 2012


STATUS

approved



