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A194489 Number of ways to arrange 5 nonattacking knights on the lower triangle of an n X n board 1
0, 0, 0, 13, 387, 3727, 23496, 111433, 429343, 1407755, 4061432, 10561723, 25208796, 55996244, 117021864, 232070481, 439779278, 800893832, 1408234986, 2400123737, 3978154435, 6430366713, 10161044648, 15728568633, 23892962265, 35675014169 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

COMMENTS

Column 5 of A194492

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..68

FORMULA

Empirical: a(n) = (1/3840)*n^10 + (1/768)*n^9 - (17/384)*n^8 + (3/128)*n^7 + (951/256)*n^6 - (68939/3840)*n^5 - (1433/12)*n^4 + (230047/192)*n^3 - (149581/240)*n^2 - (718267/30)*n + 72425 for n>10

EXAMPLE

Some solutions for 4X4

..1........1........0........0........1........1........1........1

..0.0......0.1......0.1......0.1......1.1......1.0......0.0......0.0

..1.0.1....1.0.1....1.0.1....1.1.1....1.0.0....0.0.0....0.0.0....0.0.1

..0.1.0.1..0.1.0.0..0.1.0.1..0.1.0.0..0.0.0.1..1.0.1.1..1.1.1.1..0.1.1.1

CROSSREFS

Sequence in context: A267433 A142122 A302700 * A275651 A203972 A013527

Adjacent sequences:  A194486 A194487 A194488 * A194490 A194491 A194492

KEYWORD

nonn

AUTHOR

R. H. Hardin Aug 26 2011

STATUS

approved

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Last modified April 14 05:00 EDT 2021. Contains 342941 sequences. (Running on oeis4.)