OFFSET
1,1
COMMENTS
Column 2 of A222779.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 39*a(n-1) - 399*a(n-2) + 1261*a(n-3) - 900*a(n-4) for n>6.
Conjectures from Colin Barker, Aug 16 2018: (Start)
G.f.: x*(2 - 71*x + 559*x^2 - 667*x^3 - 1779*x^4 + 660*x^5) / ((1 - x)*(1 - 4*x)*(1 - 9*x)*(1 - 25*x)).
a(n) = 9/4 + 2^(2*n-3) + 5*3^(2*n-5) + (7/4)*5^(2*n-5) for n>2.
(End)
EXAMPLE
Some solutions for n=3:
..0..0....0..1....0..1....0..1....0..1....0..1....0..1....0..1....0..1....0..1
..1..2....2..2....2..1....2..1....0..2....2..3....2..3....2..3....2..3....2..2
..3..4....1..3....3..3....3..4....3..2....1..0....2..3....4..4....2..0....3..4
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 05 2013
STATUS
approved