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A015164
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Theta series of 17-dimensional lattice Q'_17(6)^{+3}.
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8
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1, 0, 0, 0, 102, 0, 1326, 9792, 0, 31552, 122196, 0, 240618, 992256, 0, 1452480, 4163742, 0, 5030028, 17109888, 0, 18128256, 45317988, 0, 43527174, 134013312, 0, 119299200, 276648888, 0, 232127928, 672628800, 0, 537564480, 1186603368, 0, 910537442, 2535618816, 0, 1881950592, 4014830772, 0, 2894860164, 7826947968, 0, 5501926784, 11452412304, 0, 7880557842, 20846939520, 0
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OFFSET
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0,5
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LINKS
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Table of n, a(n) for n=0..50.
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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EXAMPLE
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1 + 102*q^8 + 1326*q^12 + 9792*q^14 + 31552*q^18 + 122196*q^20 + 240618*q^24 + 992256*q^26 + 1452480*q^30 + ...
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PROG
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(PARI) \\ system("wget https://oeis.org/A015164/a015164.txt");
g = matconcat(read("a015164.txt")~);
seq(N, g, flag=0) = concat(1, 2*Vec(qfrep(g, N, flag)));
seq(22, g, 1) \\ Gheorghe Coserea, Nov 28 2018
(PARI)
GramMatrix()={my(p=[8 , -1 , -1 , -1 , -1 , -1 , 2 , 2 , -1 , -1 , 2 , 2 , -1 , -1 , -1 , -1 , -1]); matrix(#p, #p, i, j, p[(i-j) %#p + 1])}
a(n)={if(n==0, 1, 2*qfrep(GramMatrix(), n, 1)[n])} \\ Andrew Howroyd, Nov 29 2018
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CROSSREFS
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Cf. A015158, A015159, A015160, A015161, A015162, A015163, A015165.
Sequence in context: A259199 A006064 A230304 * A325776 A325775 A204749
Adjacent sequences: A015161 A015162 A015163 * A015165 A015166 A015167
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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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