OFFSET
0,2
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..1000
M. Baake and U. Grimm, Coordination sequences for root lattices and related graphs, arXiv:cond-mat/9706122, Zeit. f. Kristallographie, 212 (1997), 253-256.
R. Bacher, P. de la Harpe and B. Venkov, Séries de croissance et séries d'Ehrhart associées aux réseaux de racines, C. R. Acad. Sci. Paris, 325 (Series 1) (1997), 1137-1142.
J. H. Conway and N. J. A. Sloane, Low-Dimensional Lattices VII: Coordination Sequences, Proc. Royal Soc. London, A453 (1997), 2369-2389 (pdf).
M. O'Keeffe, Coordination sequences for lattices, Zeit. f. Krist., 210 (1995), 905-908.
M. O'Keeffe, Coordination sequences for lattices, Zeit. f. Krist., 210 (1995), 905-908. [Annotated scanned copy]
Index entries for linear recurrences with constant coefficients, signature (5, -10, 10, -5, 1).
FORMULA
a(n) = 2*(9*n^2+1)*(n^2+1) (see MAPLE line).
G.f.: (1+x)*(1+34*x+146*x^2+34*x^3+x^4)/(1-x)^5. [Colin Barker, Apr 14 2012]
MAPLE
2*(9*n^2+1)*(n^2+1);
MATHEMATICA
CoefficientList[Series[(1+x)*(1+34*x+146*x^2+34*x^3+x^4)/(1-x)^5, {x, 0, 30}], x] (* Vincenzo Librandi, Apr 16 2012 *)
PROG
(Magma) [1]cat[2*(9*n^2+1)*(n^2+1): n in [1..30]]; // Vincenzo Librandi, Apr 16 2012
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
STATUS
approved