OFFSET
1,2
COMMENTS
Column 1 of A222871.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 11*a(n-1) - 41*a(n-2) + 61*a(n-3) - 30*a(n-4) for n>6.
Empirical g.f.: x*(1 + x)*(1 - 10*x + 32*x^2 - 37*x^3 + 11*x^4) / ((1 - x)*(1 - 2*x)*(1 - 3*x)*(1 - 5*x)). - Colin Barker, Aug 16 2018
EXAMPLE
All solutions for n=3:
..0....0....0
..1....1....0
..2....1....1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 07 2013
STATUS
approved