OFFSET
1,2
COMMENTS
Column 1 of A270118.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 14*a(n-1) - 49*a(n-2).
Conjectures from Colin Barker, Mar 22 2018: (Start)
G.f.: 8*x^2 / (1 - 7*x)^2.
a(n) = 8*7^(n-2)*(n-1).
(End)
EXAMPLE
Some solutions for n=4:
..5. .5. .6. .5. .0. .4. .7. .4. .4. .5. .7. .0. .7. .7. .1. .5
..6. .5. .2. .2. .7. .3. .1. .3. .5. .2. .1. .4. .6. .2. .3. .0
..7. .2. .2. .2. .1. .3. .6. .1. .3. .4. .6. .3. .1. .6. .4. .7
..0. .3. .5. .3. .2. .6. .6. .5. .4. .0. .7. .6. .7. .1. .5. .7
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 11 2016
STATUS
approved