A181207 Number of n X 3 binary matrices with no two 1's adjacent diagonally or antidiagonally.

8, 25, 119, 484, 2117, 9025, 38936, 167281, 720083, 3097600, 13329209, 57350329, 246768392, 1061782225, 4568619071, 19657722436, 84582794333, 363940725625, 1565955363224, 6737954403049, 28991906279867, 124745667481600

Offset

1,1

Comments

Column 3 of A181212.

Links

R. H. Hardin, Table of n, a(n) for n=1..400

Formula

Empirical: a(n) = 5*a(n-1) - 15*a(n-3) + 9*a(n-4).

Empirical g.f.: x*(8 - 15*x - 6*x^2 + 9*x^3) / ((1 - 5*x + 3*x^2)*(1 - 3*x^2)). - Colin Barker, Mar 26 2018

Crossrefs

Cf. A181212.

Sequence in context: A335769 A139026 A135942 * A068315 A069586 A253237

Adjacent sequences: A181204 A181205 A181206 * A181208 A181209 A181210

Keyword

nonn

Author

R. H. Hardin, Oct 10 2010

Status

approved