A243709 Coxeter numbers of the D-type Niemeier root systems.

6, 10, 14, 18, 22, 30, 46

Offset: 1

Author

N. J. A. Sloane, Jun 19 2014

Keywords

• nonn
• fini
• full

Comments

These are exactly the even integers 2n such that the group Gamma_0(2n)+n has genus zero.

Links

• Miranda C. N. Cheng, John F. R. Duncan and Jeffrey A. Harvey, Umbral moonshine and the Niemeier lattices, Research in the Mathematical Sciences, 2014, 1:3. See Eq. (23).

Crossrefs

Cf. A091401.

Formula

a(n) = 2*A133848(n+11). - Omar E. Pol, Dec 20 2014