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

1, 0, 800, 0, 107200, 0, 5831520, 0, 174074240, 0, 3340028320, 10485760, 45553842240, 807403520, 474040586720, 22284337152, 3959316509440, 344876646400, 27528013314080, 3621204787200, 163698115739072

Offset

0,3

Links

Ray Chandler, Table of n, a(n) for n = 0..1001

J. H. Conway and N. J. A. Sloane, Low-Dimensional Lattices VII: Coordination Sequences, Proc. Royal Soc. London, A453 (1997), 2369-2389 (pdf).

Joan Serra-Sagrista, Enumeration of lattice points in l_1 norm, Inf. Proc. Lett. 76 (1-2) (2000) 39-44.

Index entries for linear recurrences with constant coefficients, 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).

Maple

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.

Crossrefs

Sequence in context: A101039 A121642 A364087 * A283899 A043404 A015065

Adjacent sequences: A035883 A035884 A035885 * A035887 A035888 A035889

Keyword

nonn

Author

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

Extensions

Recomputed by N. J. A. Sloane, Nov 27 1998

Status

approved