A035810 Coordination sequence for lattice D*_50 (with edges defined by l_1 norm = 1).

1, 100, 5000, 166700, 4170000, 83500020, 1394447000, 19980314300, 250799764000, 2802204288900, 28222682700200, 258862555329100, 2180706863326000, 16993705726247700, 123252789641763000, 836413142574501340

Offset: 0

Author

N. J. A. Sloane, J. Serra-Sagrista (jserra(AT)ccd.uab.es)

Keywords

• nonn

Comments

Differs from A035745 first at a(25), a(26), a(27), etc. - R. J. Mathar, Oct 24 2008

Links

• 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 (50, -1225, 19600, -230300, 2118760, -15890700, 99884400, -536878650, 2505433700, -10272278170, 37353738800, -121399651100, 354860518600, -937845656300, 2250829575120, -4923689695575, 9847379391150, -18053528883775, 30405943383200, -47129212243960, 67327446062800, -88749815264600, 108043253365600, -121548660036300, 126410606437752, -121548660036300, 108043253365600, -88749815264600, 67327446062800, -47129212243960, 30405943383200, -18053528883775, 9847379391150, -4923689695575, 2250829575120, -937845656300, 354860518600, -121399651100, 37353738800, -10272278170, 2505433700, -536878650, 99884400, -15890700, 2118760, -230300, 19600, -1225, 50, -1).

Formula

a(m) = (Sum_{k=0..n} 2^k*binomial(n, k)*binomial(m-1, k-1)) + 2^n*binomial((n+2*m)/2-1, n-1); with n=50.