A278303 - OEIS

%I #6 May 27 2021 14:14:44

%S 3,32,294,2089,11486,51562,197981,672365,2068221,5862308,15508725,

%T 38669253,91572377,207221995,450353206,943885459,1914477373,

%U 3769095759,7220896420,13492019950,24634260906,44027466111,77141909955,132687309790

%N Number of n X 2 0..2 arrays with rows and columns in lexicographic nondecreasing order but with exactly one mistake.

%C Column 2 of A278309.

%H R. H. Hardin, <a href="/A278303/b278303.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = (1/355687428096000)*n^17 + (1/2324754432000)*n^16 + (31/1046139494400)*n^15 + (431/348713164800)*n^14 + (4033/114960384000)*n^13 + (27523/38320128000)*n^12 + (882599/80472268800)*n^11 + (103841/812851200)*n^10 + (164889503/146313216000)*n^9 + (350473933/48771072000)*n^8 + (90321617/2874009600)*n^7 + (163135657/1916006400)*n^6 + (55992583019/435891456000)*n^5 + (35685265529/145297152000)*n^4 + (926078371/1210809600)*n^3 + (234481327/201801600)*n^2 + (180371/314160)*n.

%e Some solutions for n=4

%e ..0..2. .0..0. .1..1. .1..2. .1..2. .0..2. .0..1. .0..2. .0..2. .0..1

%e ..0..0. .0..0. .0..0. .2..1. .0..0. .0..0. .0..0. .2..0. .0..2. .0..2

%e ..0..0. .1..0. .1..2. .2..2. .1..1. .2..0. .0..1. .0..1. .0..2. .0..1

%e ..2..0. .1..0. .1..2. .2..0. .2..1. .2..1. .0..2. .2..1. .0..0. .0..2

%Y Cf. A278309.

%K nonn

%O 1,1

%A _R. H. Hardin_, Nov 17 2016