|
| |
|
|
A117574
|
|
Total number of permutations p of [n] such that |p(i+3) - p(i)| is not equal to 3 for 1 <= i <= n-3.
|
|
8
| |
|
|
1, 2, 6, 20, 80, 384, 2240, 15424, 123456, 1110928, 11287232, 127016304, 1565107248, 20935873872, 301974271248, 4669727780624, 77046043259824, 1350585114106416, 25062108668100208, 490725684463001488, 10109820295907492304
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 1,2
|
|
|
COMMENTS
| a(n) is also number of ways to place n nonattacking pieces rook + leaper[3,3] on an n X n chessboard.
|
|
|
REFERENCES
| Roberto Tauraso, The Dinner Table Problem: The Rectangular Case, INTEGERS, vol. 6 (2006), paper A11.
|
|
|
LINKS
| V. Kotesovec, Number of ways of placing non-attacking queens, kings, bishops and knights (in English and Czech)
Vaclav Kotesovec, Table of n, a(n) for n=1..28
Vaclav Kotesovec, Mathematica program for this sequence
|
|
|
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
| Cf. A002464, A110128.
Sequence in context: A108124 A204440 A189839 * A177481 A177475 A118476
Adjacent sequences: A117571 A117572 A117573 * A117575 A117576 A117577
|
|
|
KEYWORD
| nonn
|
|
|
AUTHOR
| James A. Sellers (sellersj(AT)math.psu.edu), Apr 27 2006
|
|
|
EXTENSIONS
| Terms a(17)-a(28) from Vaclav Kotesovec (kotesovec(AT)chello.cz), Apr 19 2011
|
| |
|
|
