A207255 Number of 4 X n 0..1 arrays avoiding 0 0 1 and 1 0 1 horizontally and 0 1 0 and 1 0 1 vertically.

10, 100, 370, 940, 1950, 3560, 5950, 9320, 13890, 19900, 27610, 37300, 49270, 63840, 81350, 102160, 126650, 155220, 188290, 226300, 269710, 319000, 374670, 437240, 507250, 585260, 671850, 767620, 873190, 989200, 1116310, 1255200, 1406570

Offset

1,1

Comments

Row 4 of A207254.

Links

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

Formula

Empirical: a(n) = (5/6)*n^4 + (35/3)*n^3 - (5/6)*n^2 - (5/3)*n.

Conjectures from Colin Barker, Jun 21 2018: (Start)

G.f.: 10*x*(1 + 5*x - 3*x^2 - x^3) / (1 - x)^5.

a(n) = 5*a(n-1) - 10*a(n-2) + 10*a(n-3) - 5*a(n-4) + a(n-5) for n>5.

(End)

Example

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

Crossrefs

Cf. A207254.

Sequence in context: A207520 A207919 A208699 * A207950 A207859 A207809

Adjacent sequences: A207252 A207253 A207254 * A207256 A207257 A207258

Keyword

nonn

Author

R. H. Hardin, Feb 16 2012

Status

approved