A302681 Number of 3Xn 0..1 arrays with every element equal to 0, 1, 4 or 6 horizontally, diagonally or antidiagonally adjacent elements, with upper left element zero.

4, 4, 8, 12, 18, 40, 94, 184, 358, 760, 1594, 3220, 6574, 13636, 28078, 57460, 118090, 243232, 499846, 1026496, 2110462, 4339696, 8918722, 18329596, 37680070, 77455324, 159200278, 327229276, 672635458, 1382602264, 2841890926, 5841485128

Offset

1,1

Comments

Row 3 of A302680.

Links

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

Formula

Empirical: a(n) = a(n-1) +3*a(n-3) +3*a(n-4) for n>7

Example

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

Crossrefs

Cf. A302680.

Sequence in context: A003829 A194697 A194696 * A002368 A299474 A022087

Adjacent sequences: A302678 A302679 A302680 * A302682 A302683 A302684

Keyword

nonn

Author

R. H. Hardin, Apr 11 2018

Status

approved