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A035604
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Number of points of L1 norm 10 in cubic lattice Z^n.
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3
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0, 2, 40, 402, 2720, 14002, 58728, 209762, 658048, 1854882, 4780008, 11414898, 25534368, 53972178, 108568488, 209070018, 387328512, 693230658, 1202893992, 2029779538, 3339504032, 5369283570, 8453107432, 13053926690, 19804348032, 29557550050, 43450388072
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OFFSET
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0,2
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LINKS
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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 (11, -55, 165, -330, 462, -462, 330, -165, 55, -11, 1).
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FORMULA
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a(n) = 2n^2/14175 * (2n^8 + 120n^6 + 1806n^4 + 7180n^2 + 5067).
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MAPLE
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f := proc(d, m) local i; sum( 2^i*binomial(d, i)*binomial(m-1, i-1), i=1..min(d, m)); end; # n=dimension, m=norm
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MATHEMATICA
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f[d_, m_] := Sum[2^i*Binomial[d, i]*Binomial[m-1, i-1], {i, 1, Min[d, m]}];
a[n_] := f[n, 10];
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PROG
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(PARI) x='x+O('x^99); concat(0, Vec(2*x*(1+x)^9/(1-x)^11)) \\ Altug Alkan, Mar 12 2018
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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