A008388 Crystal ball sequence for A_6 lattice.
1, 43, 505, 3067, 12559, 39733, 104959, 242845, 507781, 980407, 1775005, 3047815, 5006275, 7919185, 12127795, 18057817, 26232361, 37285795, 51978529, 71212723, 96048919, 127723597, 167667655
Offset: 0
Links
- T. D. Noe, Table of n, a(n) for n = 0..1000
- J. H. Conway and N. J. A. Sloane, Low-Dimensional Lattices VII: Coordination Sequences, Proc. Royal Soc. London, A453 (1997), 2369-2389 (pdf).
- Index entries for crystal ball sequences
- Index entries for linear recurrences with constant coefficients, signature (7, -21, 35, -35, 21, -7, 1).
Programs
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Maxima
A008388[n]:=1+7*n*(n+1)*(n^2+n+3)*(11*n^2+11*n+14)/60$ makelist(A008388[n],n,0,30); /* Martin Ettl, Oct 26 2012 */
Formula
a(n) = 1+7*n*(n+1)*(n^2+n+3)*(11*n^2+11*n+14)/60. - T. D. Noe, Apr 29 2007
G.f.: (1+36*x+225*x^2+400*x^3+225*x^4+36*x^5+x^6)/(1-x)^7. [Colin Barker, Mar 15 2012]
Comments