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A278628 Number of nX2 0..2 arrays with rows in nondecreasing lexicographic order and columns in nonincreasing lexicographic order, but with exactly two mistakes. 1
0, 13, 285, 3354, 27521, 175881, 932205, 4266912, 17344954, 63898594, 216606040, 683599110, 2027209742, 5691010421, 15216367989, 38944866772, 95817126997, 227430633270, 522402290790, 1164311022921, 2523775686270, 5331359865045 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Column 2 of A278634.

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..210

FORMULA

Empirical: a(n) = (1/620448401733239439360000)*n^24 + (1/2248001455555215360000)*n^23 + (61/1037539133333176320000)*n^22 + (23/4644631106519040000)*n^21 + (104341/350337889177436160000)*n^20 + (6949/512189896458240000)*n^19 + (710713/1466725612584960000)*n^18 + (37298267/2688996956405760000)*n^17 + (2447539049/7592461994557440000)*n^16 + (3869390387/632705166213120000)*n^15 + (564645080393/5965505852866560000)*n^14 + (32796029107/27618082652160000)*n^13 + (996499793624389/83517081940131840000)*n^12 + (59819000678947/632705166213120000)*n^11 + (84816399097571/146008884510720000)*n^10 + (428014613650991/158176291553280000)*n^9 + (1006691142411629/104766115184640000)*n^8 + (827938404705089/32011868528640000)*n^7 + (70267771340481037/1419192838103040000)*n^6 + (7292384715686149/118266069841920000)*n^5 + (279991448485477/7227370934784000)*n^4 - (11564797442491/361368546739200)*n^3 - (14612582504501/148419224553600)*n^2 - (71459/1225224)*n

EXAMPLE

Some solutions for n=4

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

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

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

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

CROSSREFS

Cf. A278634.

Sequence in context: A256044 A160294 A092145 * A035017 A064750 A228753

Adjacent sequences:  A278625 A278626 A278627 * A278629 A278630 A278631

KEYWORD

nonn

AUTHOR

R. H. Hardin, Nov 24 2016

STATUS

approved

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Last modified December 7 04:21 EST 2021. Contains 349567 sequences. (Running on oeis4.)