cp's OEIS Frontend

A278628 Number of nX2 0..2 arrays with rows in nondecreasing lexicographic order and columns in nonincreasing lexicographic order, but with exactly two mistakes.

%I A278628 #5 Nov 24 2016 10:18:43
%S A278628 0,13,285,3354,27521,175881,932205,4266912,17344954,63898594,
%T A278628 216606040,683599110,2027209742,5691010421,15216367989,38944866772,
%U A278628 95817126997,227430633270,522402290790,1164311022921,2523775686270,5331359865045
%N A278628 Number of nX2 0..2 arrays with rows in nondecreasing lexicographic order and columns in nonincreasing lexicographic order, but with exactly two mistakes.
%C A278628 Column 2 of A278634.
%H A278628 R. H. Hardin, <a href="/A278628/b278628.txt">Table of n, a(n) for n = 1..210</a>
%F A278628 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
%e A278628 Some solutions for n=4
%e A278628 ..2..0. .0..0. .0..1. .0..1. .1..0. .2..1. .1..2. .2..2. .1..1. .1..0
%e A278628 ..1..2. .1..2. .2..2. .1..2. .2..0. .1..0. .0..0. .0..1. .0..1. .0..2
%e A278628 ..2..2. .2..1. .0..1. .2..1. .1..1. .0..0. .1..1. .1..2. .0..2. .0..0
%e A278628 ..0..0. .1..0. .2..1. .0..0. .0..1. .2..0. .2..2. .2..2. .1..1. .1..2
%Y A278628 Cf. A278634.
%K A278628 nonn
%O A278628 1,2
%A A278628 _R. H. Hardin_, Nov 24 2016