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A019562 Coordination sequence for C_6 lattice. 3
1, 72, 912, 5336, 20256, 58728, 142000, 301560, 581184, 1038984, 1749456, 2805528, 4320608, 6430632, 9296112, 13104184, 18070656, 24442056, 32497680, 42551640, 54954912, 70097384, 88409904, 110366328, 136485568, 167333640, 203525712, 245728152, 294660576 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Seiichi Manyama, Table of n, a(n) for n = 0..10000

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.

FORMULA

G.f.: (1+6*x+x^2)*(1+60*x+134*x^2+60*x^3+x^4)/(1-x)^6.

a(n) = A008414(2*n). - Seiichi Manyama, Jun 08 2018

MATHEMATICA

Join[{1}, LinearRecurrence[{6, -15, 20, -15, 6, -1}, {72, 912, 5336, 20256, 58728, 142000}, 28]] (* Jean-François Alcover, Dec 08 2018 *)

CROSSREFS

Cf. A008414.

Sequence in context: A082949 A240983 A210627 * A250423 A250650 A008399

Adjacent sequences:  A019559 A019560 A019561 * A019563 A019564 A019565

KEYWORD

nonn

AUTHOR

Michael Baake (mbaake(AT)sunelc3.tphys.physik.uni-tuebingen.de)

STATUS

approved

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Last modified October 21 14:47 EDT 2019. Contains 328301 sequences. (Running on oeis4.)