OFFSET
1,1
COMMENTS
Column 2 of A223449.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 6*a(n-1) - 8*a(n-2) for n>3.
Conjectures from Colin Barker, Aug 20 2018: (Start)
G.f.: 4*x*(7 - 16*x + 2*x^2) / ((1 - 2*x)*(1 - 4*x)).
a(n) = 2^(n-2) * (4+25*2^n) for n>1.
(End)
EXAMPLE
Some solutions for n=3:
.10.13....1..0....9.11....4..7...10..2...12..9....1..3....1..4....3..5....4..1
.13.10....3..1....2..9....8..4...14.10....9.12....3..6....3..1....6..3....1..0
.10.14....5..3....0..2....4..8...10.13....2..9....1..3....1..3....3..1....4..1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 20 2013
STATUS
approved