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A008921 Coordination sequence for lattice {E_7}*. 1
1, 56, 938, 7688, 39746, 150248, 455114, 1171928, 2668610, 5521880, 10585514, 19068392, 32622338, 53439752, 84361034, 128991800, 191829890, 278402168, 395411114, 550891208, 754375106, 1017069608 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

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 linear recurrences with constant coefficients, signature (7, -21, 35, -35, 21, -7, 1).

FORMULA

G.f.: (x+1)*(x^6+624*x^5+1959*x^4+1744*x^3+519*x^2+48*x+1)/(1-x)^7.

MAPLE

68/5*n^6-216/5*n^5+148*n^4-192*n^3+902/5*n^2-264/5*n+2;

CROSSREFS

Sequence in context: A182866 A008389 A219937 * A252181 A251432 A243206

Adjacent sequences:  A008918 A008919 A008920 * A008922 A008923 A008924

KEYWORD

nonn

AUTHOR

N. J. A. Sloane.

STATUS

approved

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Last modified January 17 23:15 EST 2019. Contains 319251 sequences. (Running on oeis4.)