A206537 Number of (n+1) X 4 0..2 arrays with the number of clockwise edge increases in 2 X 2 subblocks nondecreasing, and counterclockwise edge increases nonincreasing, rightwards and downwards.

1620, 14781, 141759, 1419921, 14528199, 150387285, 1567749888, 16417626507, 172416155157, 1814112395499, 19110547682607, 201479426103099, 2125267836114957, 22425737682248088, 236688761385595083

Offset

1,1

Comments

Column 3 of A206542.

Links

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

Formula

Empirical: a(n) = 26*a(n-1) -169*a(n-2) -962*a(n-3) +15074*a(n-4) -23548*a(n-5) -388835*a(n-6) +1661306*a(n-7) +3387121*a(n-8) -32428954*a(n-9) +18217134*a(n-10) +298256916*a(n-11) -598690104*a(n-12) -1238898284*a(n-13) +4947375888*a(n-14) +248363732*a(n-15) -19612727472*a(n-16) +17680860320*a(n-17) +37546981780*a(n-18) -68886915424*a(n-19) -19805672744*a(n-20) +117856544624*a(n-21) -46294103104*a(n-22) -94823075520*a(n-23) +86888550208*a(n-24) +22051127568*a(n-25) -55468199168*a(n-26) +13452820320*a(n-27) +12246999328*a(n-28) -7344098112*a(n-29) +380505984*a(n-30) +639121152*a(n-31) -167178240*a(n-32) +11612160*a(n-33) for n>37.

Example

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

Crossrefs

Sequence in context: A277111 A345597 A345856 * A269278 A269184 A269150

Adjacent sequences: A206534 A206535 A206536 * A206538 A206539 A206540

Keyword

nonn

Author

R. H. Hardin, Feb 09 2012

Status

approved