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Coordination sequence for lattice D*_20 (with edges defined by l_1 norm = 1).
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%I #11 Sep 05 2023 15:04:55

%S 1,40,800,10680,107200,864008,5831520,33940120,174074240,800061160,

%T 3340552608,12819218040,45663942720,152270990280,478683156960,

%U 1426865410392,4052167914240,11006991835560,28691971995680,71976895917880

%N Coordination sequence for lattice D*_20 (with edges defined by l_1 norm = 1).

%H Joan Serra-Sagrista, <a href="http://dx.doi.org/10.1016/S0020-0190(00)00119-8">Enumeration of lattice points in l_1 norm</a>, Inf. Proc. Lett. 76 (1-2) (2000) 39-44.

%H <a href="/index/Rec#order_20">Index entries for linear recurrences with constant coefficients</a>, signature (20, -190, 1140, -4845, 15504, -38760, 77520, -125970, 167960, -184756, 167960, -125970, 77520, -38760, 15504, -4845, 1140, -190, 20, -1).

%F a(m)=add(2^k*binomial(n, k)*binomial(m-1, k-1), k=0..n)+2^n*binomial((n+2*m)/2-1, n-1); with n=20.

%K nonn

%O 0,2

%A _N. J. A. Sloane_, J. Serra-Sagrista (jserra(AT)ccd.uab.es)