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A189271 Number of permutations p of 1,2,...,n satisfying |p(i+6)-p(i)|<>6 for all 1<=i<=n-6. 4
1, 2, 6, 24, 120, 720, 4800, 34752, 280512, 2528256, 25282560, 278323200, 3289036800, 42336448512, 589351062528, 8820501301248, 141215147788800, 2407845089203200, 43543159894318080, 832618225074748416, 16782891792284791296 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

a(n) is also number of ways to place n nonattacking pieces rook + leaper[6,6] 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..24

V. Kotesovec, Number of ways of placing non-attacking 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 + 20/n + 168/n^2)/e^2.

Generally (for this sequence is d=6): 1/e^2*(1+4(d-1)/n+2d*(3d-4)/n^2+...).

CROSSREFS

Cf. A002464, A110128, A117574, A189255, A189256.

Sequence in context: A152362 A177543 A189842 * A152366 A147740 A147739

Adjacent sequences:  A189268 A189269 A189270 * A189272 A189273 A189274

KEYWORD

nonn,hard

AUTHOR

Vaclav Kotesovec, Apr 19 2011

EXTENSIONS

Terms a(23)-a(24) from Vaclav Kotesovec, Apr 21 2012

STATUS

approved

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Last modified September 18 01:54 EDT 2021. Contains 347504 sequences. (Running on oeis4.)