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A015159 Theta series of 17-dimensional lattice Q_17(6)^{+2}. 8
1, 0, 0, 0, 0, 0, 0, 816, 2040, 0, 0, 20400, 41956, 0, 0, 236912, 362406, 0, 0, 1236240, 1933920, 0, 0, 5861328, 7591792, 0, 0, 17201280, 24124428, 0, 0, 55003296, 65640978, 0, 0, 120568080, 158815904, 0, 0, 307510960, 350243520, 0, 0, 564643440, 715382916, 0, 0, 1246785984, 1373241708, 0, 0 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,8

LINKS

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.

EXAMPLE

1 + 816*q^7 + 2040*q^8 + 20400*q^11 + 41956*q^12 + 236912*q^15 + 362406*q^16 + 1236240*q^19 + 1933920*q^20 + 5861328*q^23 + 7591792*q^24 + 17201280*q^27 + 24124428*q^28 + ...

PROG

(PARI) \\ system("wget https://oeis.org/A015159/a015159.txt");

g = matconcat(read("a015159.txt")~);

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

seq(20, g) \\ Gheorghe Coserea, Nov 28 2018

(PARI)

GramMatrix()={my(p=[7, -1, -3, 1, 1, -1, 1, 3, -3, -3, 3, 1, -1, 1, 1, -3, -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

CROSSREFS

Cf. A015158, A015160, A015161, A015162, A015163, A015164, A015165.

Sequence in context: A183820 A272606 A235976 * A250803 A251205 A064583

Adjacent sequences:  A015156 A015157 A015158 * A015160 A015161 A015162

KEYWORD

nonn

AUTHOR

N. J. A. Sloane

EXTENSIONS

More terms from Gheorghe Coserea, Nov 28 2018

STATUS

approved

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Last modified May 21 08:53 EDT 2019. Contains 323441 sequences. (Running on oeis4.)