OFFSET
0,2
REFERENCES
Inorganic Crystal Structure Database: Collection Code 30947.
LINKS
Sean A. Irvine, Table of n, a(n) for n = 0..1000
R. W. Grosse-Kunstleve, Coordination Sequences and Encyclopedia of Integer Sequences
R. W. Grosse-Kunstleve, G. O. Brunner and N. J. A. Sloane, Algebraic Description of Coordination Sequences and Exact Topological Densities for Zeolites, Acta Cryst., A52 (1996), pp. 879-889.
FORMULA
G.f.: (1 + 5*x + 16*x^2 + 40*x^3 + 88*x^4 + 159*x^5 + 252*x^6 + 359*x^7 + 459*x^8 + 535*x^9 + 566*x^10 + 547*x^11 + 481*x^12 + 381*x^13 + 272*x^14 + 167*x^15 + 92*x^16 + 38*x^17 + 10*x^18 - x^19 - x^20 - 2*x^21) / ((1 - x)^3 * (1 + x)^3 * (1 - x + x^2) * (1 + x^2)^2 * (1 + x + x^2 + x^3 + x^4)^2). - Colin Barker, Dec 23 2015
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved