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A015163
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Theta series of 17-dimensional lattice Q'_17(6)^{+2}.
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8
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1, 0, 0, 136, 1326, 8160, 31552, 88128, 240618, 658784, 1452480, 2622216, 5030028, 10390944, 18128256, 26822464, 43527174, 77769696, 119299200, 157895592, 232127928, 379052672, 537564480, 662425536, 910537442, 1402281312, 1881950592, 2201578336, 2894860164, 4268628192, 5501926784
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OFFSET
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0,4
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LINKS
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Table of n, a(n) for n=0..30.
J. H. Conway and N. J. A. Sloane, Low-Dimensional Lattices II: Subgroups of GL(n,Z), Proc. Royal Soc. London, A 419 (1988), 29-68.
Gheorghe Coserea, Gram matrix.
G. Nebe and N. J. A. Sloane, Home page for this lattice
W. Plesken, Finite Unimodular Groups of Prime Degree and Circulants, J. Algebra, vol. 97 (1985), pp. 286-312.
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PROG
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(PARI) \\ system("wget https://oeis.org/A015163/a015163.txt");
g = matconcat(read("a015163.txt")~);
seq(N, g, flag=0) = concat(1, 2*Vec(qfrep(g, N, flag)));
seq(15, g) \\ Gheorghe Coserea, Nov 28 2018
(PARI)
GramMatrix()={my(p=[3, -1, 0, 0, 1, -1, 0, 1, 0, 0, 1, 0, -1, 1, 0, 0, -1]); matrix(#p, #p, i, j, p[(i-j) %#p + 1])}
a(n)={if(n==0, 1, 2*qfrep(GramMatrix(), n, 0)[n])} \\ Andrew Howroyd, Nov 29 2018
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CROSSREFS
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Cf. A015158, A015159, A015160, A015161, A015162, A015164, A015165.
Sequence in context: A251175 A251168 A023070 * A235190 A249985 A072897
Adjacent sequences: A015160 A015161 A015162 * A015164 A015165 A015166
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KEYWORD
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nonn
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AUTHOR
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N. J. A. Sloane
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EXTENSIONS
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More terms from Gheorghe Coserea, Nov 28 2018
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STATUS
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approved
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