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A243709
Coxeter numbers of the D-type Niemeier root systems.
0
6, 10, 14, 18, 22, 30, 46
OFFSET
1,1
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).
FORMULA
a(n) = 2*A133848(n+11). - Omar E. Pol, Dec 20 2014
CROSSREFS
Cf. A091401.
Sequence in context: A136767 A187682 A315180 * A363317 A315181 A315182
KEYWORD
nonn,fini,full
AUTHOR
N. J. A. Sloane, Jun 19 2014
STATUS
approved