A280674 Number of 2 X n 0..2 arrays with no element equal to more than one of its horizontal and antidiagonal neighbors and with new values introduced in order 0 sequentially upwards.

2, 11, 59, 338, 1917, 10893, 61880, 351541, 1997095, 11345458, 64453321, 366158041, 2080136592, 11817214849, 67133363931, 381383313234, 2166631062437, 12308588230773, 69924846394792, 397241669934877, 2256722073320511

Offset

1,1

Links

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

Formula

Empirical: a(n) = 5*a(n-1) + 6*a(n-2) - 11*a(n-3) - 7*a(n-4) + 4*a(n-5) for n>6.

Empirical g.f.: x*(1 - x)*(2 + 3*x - x^2)*(1 - 2*x^2) / ((1 + x)*(1 - 6*x + 11*x^3 - 4*x^4)). - Colin Barker, Feb 14 2019

Example

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

Crossrefs

Row 2 of A280673.

Sequence in context: A363646 A210646 A054564 * A139172 A228868 A290116

Adjacent sequences: A280671 A280672 A280673 * A280675 A280676 A280677

Keyword

nonn

Author

R. H. Hardin, Jan 07 2017

Status

approved