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A002495 Theta series of 27-dimensional unimodular lattice with root system A_1 with no parity vector of norm 3. 0
1, 0, 2, 2676, 101118, 1644784, 16044996, 110148864, 584716268, 2549726784, 9515920164, 31314134428, 92917720104, 252775518960, 638328487880, 1511740834560, 3387163064214, 7228599229760, 14768913424614, 29023937463900, 55107648867544, 101434033397472 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

REFERENCES

R. Bacher and B. B. Venkov, Réseaux entiers unimodulaires sans racine en dimension 27 et 28, in Réseaux euclidiens, designs sphériques et formes modulaires, pp. 212-267, Enseignement Math., Geneva, 2001.

LINKS

Table of n, a(n) for n=0..21.

R. Bacher and B. B. Venkov, Réseaux entiers unimodulaires sans racine en dimension 27 et 28

FORMULA

G.f.: theta3^27 - 54*theta3^19*delta8 + 218*theta3^11*delta8^2 where theta3 = A000122 and delta8 = A002408. - Sean A. Irvine, Feb 28 2020

CROSSREFS

Cf. A000122, A002408, A002434, A002490.

Sequence in context: A324426 A114067 A109119 * A242109 A078457 A128148

Adjacent sequences:  A002492 A002493 A002494 * A002496 A002497 A002498

KEYWORD

nonn

AUTHOR

N. J. A. Sloane

EXTENSIONS

More terms from Sean A. Irvine, Feb 28 2020

STATUS

approved

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Last modified April 10 23:13 EDT 2021. Contains 342877 sequences. (Running on oeis4.)