A278303 Number of n X 2 0..2 arrays with rows and columns in lexicographic nondecreasing order but with exactly one mistake.

3, 32, 294, 2089, 11486, 51562, 197981, 672365, 2068221, 5862308, 15508725, 38669253, 91572377, 207221995, 450353206, 943885459, 1914477373, 3769095759, 7220896420, 13492019950, 24634260906, 44027466111, 77141909955, 132687309790

Offset: 1

Author

R. H. Hardin, Nov 17 2016

Keywords

• nonn

Comments

Column 2 of A278309.

Examples

			Some solutions for n=4
..0..2. .0..0. .1..1. .1..2. .1..2. .0..2. .0..1. .0..2. .0..2. .0..1
..0..0. .0..0. .0..0. .2..1. .0..0. .0..0. .0..0. .2..0. .0..2. .0..2
..0..0. .1..0. .1..2. .2..2. .1..1. .2..0. .0..1. .0..1. .0..2. .0..1
..2..0. .1..0. .1..2. .2..0. .2..1. .2..1. .0..2. .2..1. .0..0. .0..2
		

Links

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

Crossrefs

Cf. A278309.

Formula

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.