A278628 Number of nX2 0..2 arrays with rows in nondecreasing lexicographic order and columns in nonincreasing lexicographic order, but with exactly two mistakes.
0, 13, 285, 3354, 27521, 175881, 932205, 4266912, 17344954, 63898594, 216606040, 683599110, 2027209742, 5691010421, 15216367989, 38944866772, 95817126997, 227430633270, 522402290790, 1164311022921, 2523775686270, 5331359865045
Offset: 1
Keywords
Examples
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
Links
- R. H. Hardin, Table of n, a(n) for n = 1..210
Crossrefs
Cf. A278634.
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
Comments