OFFSET
1,2
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 15*a(n-1) - 90*a(n-2) + 281*a(n-3) - 510*a(n-4) + 585*a(n-5) - 437*a(n-6) + 210*a(n-7) - 60*a(n-8) + 8*a(n-9) for n>10.
Empirical g.f.: x^2*(9 - 85*x + 356*x^2 - 819*x^3 + 1096*x^4 - 888*x^5 + 438*x^6 - 124*x^7 + 16*x^8) / (1 - 5*x + 5*x^2 - 2*x^3)^3. - Colin Barker, Feb 12 2019
EXAMPLE
Some solutions for n=4:
..0..1..1. .0..1..0. .0..1..0. .0..1..0. .0..1..1. .0..1..1. .0..0..1
..0..0..1. .1..1..1. .1..0..0. .1..1..1. .0..0..1. .0..1..1. .1..0..1
..1..0..0. .0..0..1. .0..1..1. .0..0..1. .1..1..1. .1..0..0. .0..1..1
..1..1..1. .1..1..0. .1..0..0. .0..0..1. .0..1..0. .1..1..0. .1..0..1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 24 2016
STATUS
approved