OFFSET
0,2
COMMENTS
Note that there may be other vertices in the Galebach list of u-uniform tilings with u <= 6 that have this same coordination sequence. See the Galebach link for the complete list of A-numbers for all these tilings.
LINKS
FORMULA
Conjectures from Chai Wah Wu, Nov 19 2025: (Start)
a(n) = 2*a(n-9) - a(n-18) for n > 21.
G.f.: (-4*x^21 + x^18 + 6*x^17 + 14*x^16 + 8*x^15 + 22*x^14 + 26*x^13 + 30*x^12 + 34*x^11 + 38*x^10 + 42*x^9 + 38*x^8 + 30*x^7 + 30*x^6 + 22*x^5 + 18*x^4 + 12*x^3 + 10*x^2 + 6*x + 1)/(x^18 - 2*x^9 + 1). (End)
CROSSREFS
KEYWORD
nonn
AUTHOR
Brian Galebach and N. J. A. Sloane, Jun 18 2018
STATUS
approved
