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

0,3

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 - 1024*theta3^3*delta8^3 where theta3 = A000122 and delta8 = A002408. - Sean A. Irvine, Feb 28 2020

Crossrefs

Cf. A000122, A002408, A002434.

Sequence in context: A201242 A062585 A239505 * A179961 A160224 A129061

Adjacent sequences: A002487 A002488 A002489 * A002491 A002492 A002493

Keyword

nonn

Author

N. J. A. Sloane

Extensions

More terms from Sean A. Irvine, Feb 28 2020

Status

approved