OFFSET
1,2
COMMENTS
Column 1 of A269767.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 10*a(n-1) - 25*a(n-2).
Conjectures from Colin Barker, Mar 22 2018: (Start)
G.f.: 6*x^2 / (1 - 5*x)^2.
a(n) = 6*5^(n-2)*(n-1).
(End)
EXAMPLE
Some solutions for n=4:
..0. .2. .4. .2. .2. .5. .1. .0. .3. .1. .1. .5. .5. .2. .4. .0
..5. .3. .1. .5. .0. .1. .0. .4. .1. .1. .5. .0. .3. .4. .5. .0
..2. .3. .3. .0. .2. .4. .5. .2. .3. .4. .0. .3. .4. .1. .1. .5
..1. .0. .5. .0. .3. .5. .4. .3. .2. .0. .2. .3. .1. .1. .4. .3
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 04 2016
STATUS
approved