OFFSET
1,3
LINKS
Alois P. Heinz, Table of n, a(n) for n = 1..10000
FORMULA
G.f.: (x^6-2*x^5+x^4-x^3+2*x^2+1)*x^2/((x^2+x+1)^2*(x-1)^4). - Alois P. Heinz, Aug 27 2016
EXAMPLE
a(6) = 14, the 14 edges are: (111111) - (21111), (21111) - (1110), (21111) - (2211), (1110) - (111), (1110) - (210), (2211) - (111), (2211) - (210), (2211) - (222), (210) - (00), (210) - (21), (111) - (21), (222) - (21), (00) - (0), (21) - (0).
CROSSREFS
KEYWORD
nonn
AUTHOR
Caleb Ji, Aug 17 2016
EXTENSIONS
More terms from Alois P. Heinz, Aug 27 2016
STATUS
approved