OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 4*a(n-1) + 34*a(n-2) - 136*a(n-3) - 369*a(n-4) + 1476*a(n-5) + 1260*a(n-6) - 5040*a(n-7).
Empirical g.f.: 24*x*(7 - 259*x^2 + 3090*x^4 - 11760*x^6) / ((1 - 4*x)*(1 - 7*x^2)*(1 - 12*x^2)*(1 - 15*x^2)). - Colin Barker, Oct 16 2018
EXAMPLE
Some solutions for n=5:
1 7 7 2 1 5 2 6 7 2 0 4 3 6 1 5 7 3 5 0
4 2 2 5 5 1 5 1 4 7 4 0 7 2 4 0 0 4 0 3
0 6 5 0 3 7 2 6 6 1 2 6 2 5 3 7 4 0 6 1
3 1 1 4 7 3 5 1 3 6 4 0 6 1 4 0 0 4 2 5
1 7 7 2 0 4 1 5 5 0 0 4 3 6 2 6 4 0 7 2
5 3 1 4 7 3 7 3 0 3 4 0 5 0 5 1 2 6 0 3
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 30 2013
STATUS
approved