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A035886 Coordination sequence for diamond structure D^+_20. (Edges defined by l_1 norm = 1.) 1

%I #16 Sep 05 2023 15:48:18

%S 1,0,800,0,107200,0,5831520,0,174074240,0,3340028320,10485760,

%T 45553842240,807403520,474040586720,22284337152,3959316509440,

%U 344876646400,27528013314080,3621204787200,163698115739072

%N Coordination sequence for diamond structure D^+_20. (Edges defined by l_1 norm = 1.)

%H Ray Chandler, <a href="/A035886/b035886.txt">Table of n, a(n) for n = 0..1001</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 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_40">Index entries for linear recurrences with constant coefficients</a>, signature (0, 20, 0, -190, 0, 1140, 0, -4845, 0, 15504, 0, -38760, 0, 77520, 0, -125970, 0, 167960, 0, -184756, 0, 167960, 0, -125970, 0, 77520, 0, -38760, 0, 15504, 0, -4845, 0, 1140, 0, -190, 0, 20, 0, -1).

%p f := proc(m) local k,t1; t1 := 2^(n-1)*binomial((n+2*m)/2-1,n-1); if m mod 2 = 0 then t1 := t1+add(2^k*binomial(n,k)*binomial(m-1,k-1),k=0..n); fi; t1; end; where n=20.

%K nonn

%O 0,3

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

%E Recomputed by _N. J. A. Sloane_, Nov 27 1998

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Last modified March 29 02:23 EDT 2024. Contains 371264 sequences. (Running on oeis4.)