cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A207590 Number of 3 X n 0..1 arrays avoiding 0 0 0 and 0 0 1 horizontally and 0 0 1 and 1 1 1 vertically.

Original entry on oeis.org

6, 36, 60, 144, 324, 756, 1728, 3996, 9180, 21168, 48708, 112212, 258336, 594972, 1369980, 3154896, 7264836, 16729524, 38524032, 88712604, 204284700, 470422512, 1083276612, 2494544148, 5744373984, 13228006428, 30461128380, 70145147664
Offset: 1

Views

Author

R. H. Hardin, Feb 19 2012

Keywords

Comments

Row 3 of A207589.

Examples

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

Crossrefs

Cf. A207589.

Formula

Empirical: a(n) = a(n-1) + 3*a(n-2) for n>4.
Conjectures from Colin Barker, Mar 05 2018: (Start)
G.f.: 6*x*(1 + 5*x + x^2 - 4*x^3) / (1 - x - 3*x^2).
a(n) = (2^(1-n)*((1-sqrt(13))^n*(-35+13*sqrt(13)) + (1+sqrt(13))^n*(35+13*sqrt(13)))) / (9*sqrt(13)) for n>2.
(End)