A253321 Number of (n+1)X(3+1) 0..1 arrays with every 2X2 subblock sum nondecreasing horizontally, vertically and antidiagonally ne-to-sw

121, 373, 1217, 2538, 6190, 11795, 25659, 48085, 99653, 188562, 382854, 736066, 1481812, 2889153, 5795537, 11413655, 22859675, 45310136, 90683516, 180442820, 361012010, 719966855, 1440188551, 2875847161, 5752209057, 11494526782

Offset

1,1

Comments

Column 3 of A253326

Links

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

Formula

Empirical: a(n) = 4*a(n-1) +2*a(n-2) -26*a(n-3) +16*a(n-4) +62*a(n-5) -70*a(n-6) -62*a(n-7) +109*a(n-8) +14*a(n-9) -76*a(n-10) +16*a(n-11) +20*a(n-12) -8*a(n-13) for n>15

Example

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

Crossrefs

Sequence in context: A208242 A167721 A330670 * A253328 A257035 A128608

Adjacent sequences: A253318 A253319 A253320 * A253322 A253323 A253324

Keyword

nonn

Author

R. H. Hardin, Dec 30 2014

Status

approved