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

 

Logo

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 56th year, we are closing in on 350,000 sequences, and we’ve crossed 9,700 citations (which often say “discovered thanks to the OEIS”).

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A187173 Number of 3-step left-handed knight's tours (moves only out two, left one) on an n X n board summed over all starting positions. 1
0, 0, 0, 16, 60, 128, 220, 336, 476, 640, 828, 1040, 1276, 1536, 1820, 2128, 2460, 2816, 3196, 3600, 4028, 4480, 4956, 5456, 5980, 6528, 7100, 7696, 8316, 8960, 9628, 10320, 11036, 11776, 12540, 13328, 14140, 14976, 15836, 16720, 17628, 18560, 19516, 20496 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

COMMENTS

Row 3 of A187172.

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..50

FORMULA

Empirical: a(n) = 12*n^2 - 64*n + 80 for n>3.

G.f.: 4*x^4*(4 - x)*(1 + x) / (1 - x)^3 (conjectured). - Colin Barker, Apr 22 2018

EXAMPLE

Some solutions for 4 X 4:

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

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

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

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

CROSSREFS

Cf. A187172.

Sequence in context: A027117 A292537 A258730 * A296958 A258731 A316125

Adjacent sequences:  A187170 A187171 A187172 * A187174 A187175 A187176

KEYWORD

nonn

AUTHOR

R. H. Hardin, Mar 06 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 December 4 08:55 EST 2021. Contains 349483 sequences. (Running on oeis4.)