A278773 Number of nX3 0..1 arrays with rows in nondecreasing lexicographic order and columns in nonincreasing lexicographic order, but with exactly two mistakes.

0, 20, 266, 1972, 10784, 48501, 189595, 665212, 2138149, 6384894, 17895624, 47447755, 119746565, 289136007, 670787381, 1500673676, 3247602855, 6817025467, 13912884597, 27665820296, 53701416899, 101922145950, 189427147850

Offset

1,2

Comments

Column 3 of A278778.

Links

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

Formula

Empirical: a(n) = (1/121645100408832000)*n^19 + (1/800296713216000)*n^18 + (193/2134124568576000)*n^17 + (1/241416806400)*n^16 + (173/1280987136000)*n^15 + (26111/7846046208000)*n^14 + (12107647/188305108992000)*n^13 + (354047/362125209600)*n^12 + (113721193/9656672256000)*n^11 + (12542321/109734912000)*n^10 + (1257109487/1379524608000)*n^9 + (1427797621/241416806400)*n^8 + (1397907414289/47076277248000)*n^7 + (598789045909/5884534656000)*n^6 + (543697174847/2615348736000)*n^5 + (191422487/1005903360)*n^4 - (3436687523/44108064000)*n^3 - (46017833/154378224)*n^2 - (3115337/19399380)*n

Example

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

Crossrefs

Cf. A278778.

Sequence in context: A229562 A021854 A025939 * A021824 A125455 A019928

Adjacent sequences: A278770 A278771 A278772 * A278774 A278775 A278776

Keyword

nonn

Author

R. H. Hardin, Nov 28 2016

Status

approved