A187302 - OEIS

The OEIS is supported by the many generous donors to the OEIS Foundation.

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 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

Other ways to Give

A187302

Number of 7-step one space leftwards or up, two space rightwards or down asymmetric rook's tours on an n X n board summed over all starting positions.

0, 0, 108, 1368, 6264, 15596, 31172, 52256, 79634, 112568, 151266, 195512, 245332, 300704, 361628, 428104, 500132, 577712, 660844, 749528, 843764, 943552, 1048892, 1159784, 1276228, 1398224, 1525772, 1658872, 1797524, 1941728, 2091484, 2246792

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,3

COMMENTS

Row 7 of A187296.

LINKS

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

FORMULA

Empirical: a(n) = 2776*n^2 - 19580*n + 30728 for n>11.

Conjectures from Colin Barker, Apr 23 2018: (Start)

G.f.: 2*x^3*(54 + 522*x + 1242*x^2 + 400*x^3 + 904*x^4 - 368*x^5 + 393*x^6 - 369*x^7 + 104*x^8 - 108*x^9 + 13*x^10 - 11*x^11) / (1 - x)^3.

a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3) for n>14.

(End)

EXAMPLE

Some solutions for 4 X 4:

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

..5..4..6..0....0..5..7..6....0..4..3..5....0..7..0..0....7..0..0..1

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

..0..0..7..0....0..0..0..0....0..0..7..6....0..0..0..0....0..4..3..2

CROSSREFS

Cf. A187296.

Sequence in context: A202092 A202484 A096953 * A269277 A115135 A202309

Adjacent sequences: A187299 A187300 A187301 * A187303 A187304 A187305

KEYWORD

nonn

AUTHOR

R. H. Hardin, Mar 08 2011

STATUS

approved