A207584 Number of n X 3 0..1 arrays avoiding 0 0 0 and 0 0 1 horizontally and 0 0 1 and 1 1 1 vertically.

6, 36, 60, 144, 312, 612, 1250, 2516, 4968, 9796, 19256, 37740, 73704, 143810, 280340, 545664, 1061676, 2064584, 4012968, 7798252, 15150258, 29428972, 57157720, 111001924, 215555184, 418562876, 812728688, 1578038530, 3063930012

Offset

1,1

Comments

Column 3 of A207589.

Links

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

Formula

Empirical: a(n) = a(n-1) + a(n-2) + 4*a(n-3) - 2*a(n-4) - a(n-5) - 8*a(n-6) + a(n-7) - 3*a(n-8) + 3*a(n-9) -2 *a(n-10) - a(n-12) for n>14.

Empirical g.f.: 2*x*(3 + 15*x + 9*x^2 + 12*x^3 - 12*x^4 - 3*x^5 - 23*x^6 + 18*x^7 - 8*x^8 + 15*x^9 - 12*x^10 + 3*x^11 - 3*x^12 + 2*x^13) / ((1 - x - x^3)*(1 - x^2 - 4*x^3 - 2*x^4 - 2*x^5 + 2*x^6 - x^7 - x^9)). - Colin Barker, Mar 05 2018

Example

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

Crossrefs

Cf. A207589.

Sequence in context: A121026 A207694 A208496 * A207590 A226119 A036148

Adjacent sequences: A207581 A207582 A207583 * A207585 A207586 A207587

Keyword

nonn

Author

R. H. Hardin, Feb 19 2012

Status

approved