A187309 Half the number of (n+2) X 3 binary arrays with each 3 X 3 subblock having sum 3, 4, 5 or 6.

210, 1472, 10262, 71836, 502545, 3516295, 24602854, 172142801, 1204456419, 8427400133, 58965241283, 412570864570, 2886695849049, 20197773668299, 141320763334969, 988799977661816, 6918483687265734, 48407582536978550

Offset

1,1

Comments

Column 1 of A187317.

Links

R. H. Hardin, Table of n, a(n) for n = 1..200

Formula

Empirical: a(n) = 7*a(n-1) + a(n-2) - 6*a(n-3) - 6*a(n-4) - 27*a(n-5) +90*a(n-6) - 81*a(n-8).

Empirical g.f.: x*(210 + 2*x - 252*x^2 - 210*x^3 - 477*x^4 + 2718*x^5 - 324*x^6 - 2592*x^7) / (1 - 7*x - x^2 + 6*x^3 + 6*x^4 + 27*x^5 - 90*x^6 + 81*x^8). - Colin Barker, Apr 23 2018

Example

Some solutions for 4 X 3 with a(1,1)=0:
..0..0..1....0..0..0....0..1..1....0..0..0....0..0..0....0..1..1....0..1..0
..1..0..1....0..0..1....0..1..1....0..1..1....0..1..0....1..0..0....0..0..1
..0..1..1....1..1..1....1..1..0....1..0..0....1..1..0....1..1..0....1..1..0
..1..0..0....1..0..0....1..0..0....0..0..1....0..0..0....0..1..1....0..1..0

Crossrefs

Cf. A187317.

Sequence in context: A328762 A047633 A187317 * A104902 A371111 A371053

Adjacent sequences: A187306 A187307 A187308 * A187310 A187311 A187312

Keyword

nonn

Author

R. H. Hardin, Mar 08 2011

Status

approved