login
A240513
Number of n X 2 0..1 arrays with no element equal to exactly two horizontal and vertical neighbors, with new values 0..1 introduced in row major order.
23
2, 3, 6, 10, 21, 42, 86, 179, 370, 770, 1601, 3330, 6930, 14419, 30006, 62442, 129941, 270410, 562726, 1171043, 2436962, 5071362, 10553601, 21962242, 45703842, 95110563, 197926886, 411889610, 857150101, 1783745642, 3712008566, 7724760339
OFFSET
1,1
COMMENTS
Column 2 of A240519.
LINKS
FORMULA
Empirical: a(n) = 2*a(n-1) + a(n-2) - a(n-3) - 2*a(n-4) + a(n-5).
Empirical g.f.: x*(2 - x)*(1 - x^2 - 2*x^3) / ((1 - x)*(1 - x - 2*x^2 - x^3 + x^4)). - Colin Barker, Feb 24 2018
Empirical: a(n) = 1+A105309(n). - R. J. Mathar, Nov 09 2018
EXAMPLE
All solutions for n=4:
..0..1....0..1....0..1....0..1....0..0....0..1....0..1....0..1....0..1....0..1
..0..0....0..1....1..0....0..1....1..1....1..0....1..1....1..0....1..0....1..0
..0..1....1..0....1..1....1..0....0..0....1..0....0..1....0..1....0..0....0..1
..1..0....1..0....1..0....0..1....1..1....0..1....1..0....1..0....1..0....0..1
CROSSREFS
Cf. A240519.
Sequence in context: A211180 A265582 A242563 * A036650 A049889 A014270
KEYWORD
nonn
AUTHOR
R. H. Hardin, Apr 06 2014
STATUS
approved