OFFSET
0,2
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 + 3*x + 7*x^2 + 15*x^3 + 28*x^4 + 40*x^5 + 50*x^6 + 59*x^7 + 70*x^8 + 76*x^9 + 71*x^10 + 63*x^11 + 52*x^12 + 40*x^13 + 28*x^14 + 19*x^15 + 7*x^16 + x^17 + x^18 - x^20) / ((1 - x)^3 * (1 + x) * (1 - x + x^2) * (1 + x^2) * (1 + x + x^2) * (1 + x^4) * (1 + x + x^2 + x^3 + x^4)). - Colin Barker, Dec 23 2015
G.f.: (1 + 4*x + 10*x^2 + 22*x^3 + 43*x^4 + 68*x^5 + 90*x^6 + 109*x^7 + 129*x^8 + 146*x^9 + 147*x^10 + 134*x^11 + 115*x^12 + 92*x^13 + 68*x^14 + 47*x^15 + 26*x^16 + 8*x^17 + 2*x^18 + x^19 - x^20 - x^21) / (1 - x^5) / (1 - x^6) / (1 - x^8). - Sean A. Irvine, Mar 15 2018
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved