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Coordination sequence for D_7 lattice.
2

%I #33 May 20 2019 03:05:05

%S 1,84,1498,11620,55650,195972,559258,1371316,2999682,6003956,11193882,

%T 19695172,33023074,53163684,82663002,124723732,183309826,263258772,

%U 370401626,511690788,695335522

%N Coordination sequence for D_7 lattice.

%H T. D. Noe, <a href="/A008359/b008359.txt">Table of n, a(n) for n = 0..1000</a>

%H M. Baake and U. Grimm, <a href="https://arxiv.org/abs/cond-mat/9706122">Coordination sequences for root lattices and related graphs</a>, arXiv:cond-mat/9706122 [cond-mat.stat-mech], 1997; Zeit. f. Kristallographie, 212 (1997), 253-256

%H R. Bacher, P. de la Harpe and B. Venkov, <a href="https://doi.org/10.1016/S0764-4442(97)83542-2">Séries de croissance et séries d'Ehrhart associées aux réseaux de racines</a>, C. R. Acad. Sci. Paris, 325 (Series 1) (1997), 1137-1142.

%H J. H. Conway and N. J. A. Sloane, Low-Dimensional Lattices VII: Coordination Sequences, Proc. Royal Soc. London, A453 (1997), 2369-2389 (<a href="http://neilsloane.com/doc/Me220.pdf">pdf</a>).

%H <a href="/index/Rec#order_07">Index entries for linear recurrences with constant coefficients</a>, signature (7,-21,35,-35,21,-7,1).

%F G.f.: (x+1)*(x^6 + 76*x^5 + 855*x^4 + 2008*x^3 + 855*x^2 + 76*x + 1)/(1-x)^7. [_Colin Barker_, Sep 26 2012; corrected by _Georg Fischer_, May 19 2019]

%p 484/45*n^6+392/9*n^4+1246/45*n^2+2;

%Y A row of array A103903.

%K nonn,easy

%O 0,2

%A _N. J. A. Sloane_ and _J. H. Conway_