A278320 Number of nX3 0..1 arrays with rows and columns in lexicographic nondecreasing order but with exactly two mistakes.

0, 20, 236, 1678, 9714, 51229, 251892, 1144205, 4762445, 18164685, 63838081, 208288721, 635843575, 1829104046, 4989647446, 12978273537, 32338548895, 77506161543, 179299342255, 401569610694, 873025241923, 1846627291485

Offset: 1

Author

R. H. Hardin, Nov 18 2016

Keywords

• nonn

Comments

Column 3 of A278325.

Examples

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

Links

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

Crossrefs

Cf. A278325.

Formula

Empirical: a(n) = (1/25852016738884976640000)*n^23 + (1/102181884343418880000)*n^22 + (1/858671297003520000)*n^21 + (1259/14597412049059840000)*n^20 + (3617/810967336058880000)*n^19 + (1831/10670622842880000)*n^18 + (13746263/2688996956405760000)*n^17 + (19040863/158176291553280000)*n^16 + (101471197/45193226158080000)*n^15 + (1480973341/45193226158080000)*n^14 + (61001884543/165708495912960000)*n^13 + (3617038307/1158800670720000)*n^12 + (1537519018181/79088145776640000)*n^11 + (13469195909881/158176291553280000)*n^10 + (4270693429711/11298306539520000)*n^9 + (9457223412823/2824576634880000)*n^8 + (218151538495819/8002967132160000)*n^7 + (775352818331437/8002967132160000)*n^6 + (627425471079349/3478413818880000)*n^5 + (3995289195644399/14783258730240000)*n^4 + (6585215991983/43020065088000)*n^3 - (217394476291/586637251200)*n^2 - (1933447697/5354228880)*n