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A035838 Coordination sequence for A_12 lattice. 2

%I

%S 1,156,6162,112268,1219374,9129276,51697802,235895244,907129236,

%T 3037849828,9079799742,24680519604,61908797418,144977296932,

%U 319917948246,670283877588,1341750437352,2579499722124,4783532975546,8588601364668,14977318285254,25437258929836

%N Coordination sequence for A_12 lattice.

%D R. Bacher, P. de la Harpe and B. Venkov, Series de croissance et series d'Ehrhart associees aux reseaux de racines, C. R. Acad. Sci. Paris, 325 (Series 1) (1997), 1137-1142.

%D J. Serra-Sagrista, Enumeration of lattice points in l_1 norm, Information Processing Letters, 76, no. 1-2 (2000), 39-44.

%H Vincenzo Librandi, <a href="/A035838/b035838.txt">Table of n, a(n) for n = 0..1000</a>

%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_12">Index entries for linear recurrences with constant coefficients</a>, signature (12, -66, 220, -495, 792, -924, 792, -495, 220, -66, 12, -1).

%F Sum_{d=1..12} C(13, d)*C(m/2 - 1, d - 1)*C(12 - d + m/2, m/2), where norm m is always even.

%F G.f.: (x^12 + 144*x^11 + 4356*x^10 + 48400*x^9 + 245025*x^8 + 627264*x^7 + 853776*x^6 + 627264*x^5 + 245025*x^4 + 48400*x^3 + 4356*x^2 + 144*x + 1) / (x - 1)^12. [_Colin Barker_, Nov 19 2012]

%t CoefficientList[Series[(x^12 + 144 x^11 + 4356 x^10 + 48400 x^9 + 245025 x^8 + 627264 x^7 + 853776 x^6 + 627264 x^5 + 245025 x^4 + 48400 x^3 + 4356 x^2 + 144 x + 1)/(x - 1)^12, {x, 0, 30}], x] (* _Vincenzo Librandi_, Oct 21 2013 *)

%K nonn,easy

%O 0,2

%A Joan Serra-Sagrista (jserra(AT)ccd.uab.es)

%E More terms from _Vincenzo Librandi_, Oct 21 2013

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Last modified August 10 12:39 EDT 2020. Contains 336379 sequences. (Running on oeis4.)