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A015162 Theta series of 17-dimensional lattice Q'_17(6). 8
1, 0, 1326, 31552, 240618, 1452480, 5030028, 18128256, 43527174, 119299200, 232127928, 537564480, 910537442, 1881950592, 2894860164, 5501926784, 7880557842, 14072683776, 19054928890, 32409323328, 42013951980, 68622996416, 85866810348, 135824277120, 164834073388, 253845438336, 300583037448 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Table of n, a(n) for n=0..26.

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 + 1326*q^4 + 31552*q^6 + 240618*q^8 + 1452480*q^10 + 5030028*q^12 + 18128256*q^14 + 43527174*q^16 + 119299200*q^18 + ...

PROG

(PARI) \\ system("wget https://oeis.org/A015162/a015162.txt");

g = matconcat(read("a015162.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, 1, -1, 1, 1, -1, 0, 2, 1, 1, 2, 0, -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

CROSSREFS

Cf. A015158, A015159, A015160, A015161, A015163, A015164, A015165.

Sequence in context: A248984 A202374 A259415 * A075037 A134116 A122390

Adjacent sequences:  A015159 A015160 A015161 * A015163 A015164 A015165

KEYWORD

nonn

AUTHOR

N. J. A. Sloane

EXTENSIONS

More terms from Gheorghe Coserea, Dec 01 2018

STATUS

approved

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Last modified October 30 12:22 EDT 2020. Contains 338079 sequences. (Running on oeis4.)