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A278408
Number of nX2 0..2 arrays with rows and columns in lexicographic nondecreasing order but with exactly two mistakes.
1
0, 20, 264, 2550, 22267, 166762, 1046418, 5586207, 25997719, 107862842, 406276442, 1409360487, 4554092377, 13832291491, 39781304005, 108983918717, 285829839116, 720662237189, 1752986235171, 4126404034476, 9424479791691, 20933182989114
OFFSET
1,2
COMMENTS
Column 2 of A278414.
FORMULA
Empirical polynomial of degree 26 (see link above)
EXAMPLE
Some solutions for n=4
..2..2. .1..1. .1..0. .0..0. .2..1. .2..0. .0..0. .2..0. .2..0. .2..1
..0..0. .0..1. .2..1. .1..0. .2..2. .0..0. .2..0. .2..1. .2..0. .2..1
..0..0. .1..2. .0..2. .2..1. .0..1. .0..0. .1..2. .0..1. .1..0. .0..2
..1..0. .0..0. .1..0. .1..1. .2..0. .1..1. .1..2. .2..0. .1..0. .2..0
CROSSREFS
Cf. A278414.
Sequence in context: A025943 A025961 A208948 * A229562 A021854 A025939
KEYWORD
nonn
AUTHOR
R. H. Hardin, Nov 21 2016
STATUS
approved