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

1,2

Comments

Column 3 of A278325.

Links

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

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

Example

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

Crossrefs

Cf. A278325.

Sequence in context: A253010 A074334 A163004 * A061139 A061121 A073398

Adjacent sequences: A278317 A278318 A278319 * A278321 A278322 A278323

Keyword

nonn

Author

R. H. Hardin, Nov 18 2016

Status

approved