OFFSET
0,2
COMMENTS
There are three types of nodes in this structure.
The coordination sequence with respect to a particular node gives the number of nodes that can be reached from that node in n steps along edges.
LINKS
Joseph Myers, Table of n, a(n) for n = 0..1000
M. E. Davis, Ordered porous materials for emerging applications, Nature, 417 (Jun 20 2002), 813-821 (gives structure).
N. J. A. Sloane, AlPO_4-11 structure, after Davis
R. J. Mathar, Illustration of counts and adjacencies (PostScript)
FORMULA
Empirical: G.f 1 +x*(3+5*x+8*x^2+7*x^3+8*x^4+9*x^5+8*x^6+7*x^7+8*x^8+5*x^9+3*x^10) / ( (x^6+x^3+1)*(x-1)^2*(1+x+x^2)^2 ) with a(n)= +a(n-3) +a(n-9) -a(n-12). - R. J. Mathar, Sep 30 2011
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
N. J. A. Sloane, Jun 28 2002
EXTENSIONS
More terms from R. J. Mathar, Mar 29 2007
Extended by Joseph Myers, Sep 29 2011
STATUS
approved