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A213963
Number of 3X3 0..n matrices with row and column 1..3 having sum <= i*n
1
138, 3186, 32060, 199735, 909900, 3323712, 10301232, 28115505, 69342790, 157454154, 333771516, 667605263, 1270560760, 2316187440, 4066346688, 6905893425, 11387501154, 18288711250, 28683554460, 44031375927, 66285794564
OFFSET
1,1
COMMENTS
Row 3 of A213962
LINKS
FORMULA
Empirical: a(n) = (n+3) *(n+2) *(449*n^5+3038*n^4+7759*n^3+9790*n^2+6264*n+1680) *(1+n)^2/10080.
EXAMPLE
Some solutions for n=4
..2..0..0....4..0..0....4..0..0....2..0..0....0..3..0....2..2..0....1..3..0
..0..0..0....0..1..2....0..2..4....0..2..2....2..1..2....2..2..2....1..4..2
..1..4..2....0..0..1....0..3..3....0..3..1....2..4..0....0..4..3....0..1..0
CROSSREFS
Sequence in context: A260133 A317579 A281592 * A279964 A163693 A089518
KEYWORD
nonn
AUTHOR
R. H. Hardin Jun 28 2012
STATUS
approved