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A187608 Number of 4-step one space for components leftwards or up, two space for components rightwards or down asymmetric quasi-bishop's tours (antidiagonal moves become knight moves) on an n X n board summed over all starting positions. 1
0, 0, 0, 28, 144, 340, 675, 1120, 1675, 2340, 3115, 4000, 4995, 6100, 7315, 8640, 10075, 11620, 13275, 15040, 16915, 18900, 20995, 23200, 25515, 27940, 30475, 33120, 35875, 38740, 41715, 44800, 47995, 51300, 54715, 58240, 61875, 65620, 69475, 73440, 77515 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

COMMENTS

Row 4 of A187606.

LINKS

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

FORMULA

Empirical: a(n) = 55*n^2 - 380*n + 640 for n>5.

Conjectures from Colin Barker, Apr 25 2018: (Start)

G.f.: x^4*(28 + 60*x - 8*x^2 + 59*x^3 - 29*x^4) / (1 - x)^3.

a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3) for n>8.

(End)

EXAMPLE

Some solutions for 5 X 5:

..0..0..0..0..0....0..0..0..1..0....0..0..0..0..4....0..0..2..0..0

..0..0..0..0..0....0..0..0..0..0....0..0..3..0..0....1..0..0..4..0

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

..1..0..0..4..0....0..0..0..4..0....0..0..0..0..1....0..0..0..0..0

..0..0..0..0..3....0..0..0..0..3....0..0..0..0..0....0..0..0..0..0

CROSSREFS

Cf. A187606.

Sequence in context: A317680 A042530 A042532 * A069917 A028380 A219887

Adjacent sequences:  A187605 A187606 A187607 * A187609 A187610 A187611

KEYWORD

nonn

AUTHOR

R. H. Hardin, Mar 11 2011

STATUS

approved

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Last modified July 28 23:26 EDT 2021. Contains 346340 sequences. (Running on oeis4.)