A002490 Theta series of 27-dimensional unimodular lattice with root system A_1 and a parity vector of norm 3.

1, 0, 2, 1652, 119550, 1497328, 16733124, 108084480, 588808172, 2544811584, 9516509988, 31328336284, 92876219432, 252846150384, 638250041288, 1511780647680, 3387237676950, 7228330859840, 14769380958438, 29023337216604, 55108233751768, 101433859301088

Offset: 0

Author

N. J. A. Sloane

Keywords

• nonn

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

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

Crossrefs

Cf. A000122, A002408, A002434.

Formula

G.f.: theta3^27 - 54*theta3^19*delta8 + 218*theta3^11*delta8^2 - 1024*theta3^3*delta8^3 where theta3 = A000122 and delta8 = A002408. - Sean A. Irvine, Feb 28 2020

Extensions

More terms from Sean A. Irvine, Feb 28 2020