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
Keywords
Examples
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
Links
- R. H. Hardin, Table of n, a(n) for n = 1..210
Crossrefs
Cf. A278778.
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
Comments