A301824 Number of 3Xn 0..1 arrays with every element equal to 1 or 2 horizontally or antidiagonally adjacent elements, with upper left element zero.

0, 5, 4, 25, 74, 278, 968, 3450, 12210, 43316, 153582, 544554, 1930920, 6846494, 24276442, 86078740, 305217538, 1082235538, 3837379072, 13606528258, 48245865110, 171069584080, 606576433502, 2150791206274, 7626248942608

Offset

1,2

Comments

Row 3 of A301823.

Links

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

Formula

Empirical: a(n) = 2*a(n-1) +6*a(n-2) -a(n-3) -3*a(n-4) +4*a(n-5) -4*a(n-6) -32*a(n-7) -9*a(n-8) -4*a(n-9) -19*a(n-10) +17*a(n-11) +3*a(n-12) +a(n-13) -a(n-14) for n>18

Example

Some solutions for n=5
..0..0..0..1..1. .0..0..1..0..1. .0..0..1..1..1. .0..0..1..1..1
..1..1..1..0..0. .0..1..0..1..0. .0..0..0..1..1. .1..1..0..1..0
..0..0..1..1..1. .1..0..1..0..0. .1..1..0..0..0. .0..0..1..0..0

Crossrefs

Cf. A301823.

Sequence in context: A288207 A038246 A176738 * A248255 A277058 A275960

Adjacent sequences: A301821 A301822 A301823 * A301825 A301826 A301827

Keyword

nonn

Author

R. H. Hardin, Mar 27 2018

Status

approved