login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A186966 Number of 3-turn queen's tours on an n X n board summed over all starting positions. 0
0, 24, 296, 1304, 3808, 8832, 17672, 31888, 53312, 84040, 126440, 183144, 257056, 351344, 469448, 615072, 792192, 1005048, 1258152, 1556280 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Row 3 of A186965.

LINKS

Table of n, a(n) for n=1..20.

FORMULA

Empirical: a(n) = 4*a(n-1)-5*a(n-2)+5*a(n-4)-4*a(n-5)+a(n-6).

Empirical: a(n) = -6*n+1/4-30*n^3+73*n^2/3+67*n^4/6-(-1)^n/4 with g.f. -8*x^2*(3+25*x+30*x^2+9*x^3) / ( (1+x)*(x-1)^5 ), all terms multiples of 8.

EXAMPLE

Some solutions for 3 X 3

..2..0..3....3..0..0....2..3..0....3..0..0....0..3..0....0..0..1....3..1..0

..0..0..0....0..2..0....0..0..0....1..2..0....0..0..2....0..0..0....0..2..0

..1..0..0....0..0..1....1..0..0....0..0..0....0..0..1....2..0..3....0..0..0

CROSSREFS

Cf. A186965.

Sequence in context: A295272 A086941 A187028 * A281134 A128598 A161524

Adjacent sequences:  A186963 A186964 A186965 * A186967 A186968 A186969

KEYWORD

nonn

AUTHOR

R. H. Hardin Mar 01 2011

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified October 25 17:22 EDT 2021. Contains 348255 sequences. (Running on oeis4.)