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A187193 Number of 6-turn rook's tours on an n X n board summed over all starting positions 0
0, 0, 1440, 40896, 364800, 1902240, 7197120, 21960960, 57407616, 133531200, 283488480, 559247040, 1038660480 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

Row 6 of A187189

LINKS

Table of n, a(n) for n=1..13.

FORMULA

Empirical: a(n) = 32*n^7 - 258*n^6 + 846*n^5 - 1426*n^4 + 1234*n^3 - 428*n^2.

Empirical G.f.: 96*x^3*(15+306*x+812*x^2+503*x^3+44*x^4)/(1-x)^8. [Colin Barker, Jan 22 2012]

EXAMPLE

Some solutions for 3X3

..0..0..1....0..0..6....3..2..1....0..0..1....0..4..5....0..0..3....0..3..2

..3..4..2....0..4..5....0..0..0....4..6..5....1..0..0....0..5..4....6..0..0

..0..5..6....2..3..1....4..5..6....3..0..2....2..3..6....1..6..2....5..4..1

CROSSREFS

Sequence in context: A061221 A238041 A187291 * A223108 A023102 A289633

Adjacent sequences:  A187190 A187191 A187192 * A187194 A187195 A187196

KEYWORD

nonn

AUTHOR

R. H. Hardin Mar 06 2011

STATUS

approved

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Last modified February 21 03:02 EST 2020. Contains 332086 sequences. (Running on oeis4.)