A278621 Number of nX2 0..2 arrays with rows in nondecreasing lexicographic order and columns in nonincreasing lexicographic order, but with exactly one mistake.

3, 46, 357, 1952, 8518, 31605, 103546, 307087, 838936, 2138608, 5137407, 11719956, 25549096, 53493458, 108027996, 211167710, 400765157, 740380790, 1334456849, 2351234708, 4056807390, 6864961455, 11409118950, 18644841765, 29994129570

Offset

1,1

Comments

Column 2 of A278627.

Links

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

Formula

Empirical: a(n) = (1/1307674368000)*n^15 + (1/12454041600)*n^14 + (149/37362124800)*n^13 + (17/136857600)*n^12 + (3497/1306368000)*n^11 + (241/5806080)*n^10 + (865163/1828915200)*n^9 + (351247/87091200)*n^8 + (2328827/93312000)*n^7 + (698341/6220800)*n^6 + (259070737/718502400)*n^5 + (30620411/39916800)*n^4 + (8765485871/9081072000)*n^3 + (2221837/3603600)*n^2 + (4873/32760)*n

Example

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

Crossrefs

Cf. A278627.

Sequence in context: A261837 A352756 A059624 * A231789 A377664 A119401

Adjacent sequences: A278618 A278619 A278620 * A278622 A278623 A278624

Keyword

nonn

Author

R. H. Hardin, Nov 24 2016

Status

approved