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A201619 Number of nX2 0..3 arrays with rows and columns lexicographically nondecreasing and every element equal to at least one horizontal or vertical neighbor 1
4, 16, 56, 211, 718, 2271, 6654, 18191, 46767, 113873, 264247, 587571, 1257743, 2602113, 5220668, 10186777, 19378603, 36016206, 65517188, 116838180, 204546828, 351977489, 595974410, 993932688, 1634127635, 2650699891, 4245165105 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 2 of A201625

LINKS

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

FORMULA

Empirical: a(n) = (1/1307674368000)*n^15 - (1/21794572800)*n^14 + (29/9340531200)*n^13 - (19/159667200)*n^12 + (4553/1026432000)*n^11 - (5303/43545600)*n^10 + (2614/893025)*n^9 - (17060387/304819200)*n^8 + (1165550053/1306368000)*n^7 - (165570521/14515200)*n^6 + (11927742139/102643200)*n^5 - (109390684973/119750400)*n^4 + (12109762378249/2270268000)*n^3 - (3278349949289/151351200)*n^2 + (6533366639/120120)*n - 63345 for n>8

EXAMPLE

Some solutions for n=9

..0..0....0..1....0..2....0..1....0..3....1..1....0..2....0..2....0..1....0..0

..2..3....0..1....0..2....0..1....0..3....1..1....0..2....0..2....0..1....0..0

..2..3....0..1....0..3....1..1....1..1....1..3....3..0....1..0....0..1....0..1

..2..3....0..2....0..3....2..1....2..0....1..3....3..0....1..0....1..1....0..1

..2..3....2..2....1..2....2..1....2..0....1..3....3..0....1..1....2..0....0..1

..3..0....2..3....1..2....2..1....3..3....1..3....3..2....2..1....2..0....0..3

..3..0....2..3....2..0....2..2....3..3....3..2....3..2....2..1....2..0....0..3

..3..1....3..3....2..0....3..1....3..3....3..2....3..2....2..1....2..0....2..2

..3..1....3..3....2..0....3..1....3..3....3..2....3..2....2..2....2..0....3..3

CROSSREFS

Sequence in context: A006079 A218263 A290908 * A197532 A220106 A281064

Adjacent sequences:  A201616 A201617 A201618 * A201620 A201621 A201622

KEYWORD

nonn

AUTHOR

R. H. Hardin Dec 03 2011

STATUS

approved

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Last modified January 20 03:25 EST 2022. Contains 350467 sequences. (Running on oeis4.)