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A015158 Theta series of 17-dimensional lattice Q_17(6). 8
1, 0, 2040, 41956, 362406, 1933920, 7591792, 24124428, 65640978, 158815904, 350243520, 715382916, 1373241708, 2505490464, 4367865216, 7321237204, 11884992774, 18736213536, 28751284680, 43126730772, 63361584408, 91360506752, 129562966320, 180742158696, 248590240202, 337956307872 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Table of n, a(n) for n=0..25.

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.

EXAMPLE

1 + 2040*q^4 + 41956*q^6 + 362406*q^8 + 1933920*q^10 + 7591792*q^12 + 24124428*q^14 + 65640978*q^16 + 158815904*q^18 + 350243520*q^20 + 715382916*q^22 + 1373241708*q^24 + 2505490464*q^26 + 4367865216*q^28 + 7321237204*q^30 + ...

PROG

(PARI) \\ system("wget https://oeis.org/A015158/a015158.txt");

g = matconcat(read("a015158.txt")~);

seq(N, g, flag=0) = concat(1, 2*Vec(qfrep(g, N, flag)));

seq(10, g, 1) \\ Gheorghe Coserea, Nov 28 2018

(PARI)

GramMatrix()={my(p=[4, 2, 1, 1, 1, 0, -1, -2, -1, -1, -2, -1, 0, 1, 1, 1, 2]); 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

CROSSREFS

Cf. A015159, A015160, A015161, A015162, A015163, A015164, A015165.

Sequence in context: A186045 A258965 A250009 * A015286 A172594 A115553

Adjacent sequences:  A015155 A015156 A015157 * A015159 A015160 A015161

KEYWORD

nonn

AUTHOR

N. J. A. Sloane

EXTENSIONS

More terms from Gheorghe Coserea, Nov 29 2018

STATUS

approved

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Last modified February 27 12:47 EST 2020. Contains 332306 sequences. (Running on oeis4.)