A239048 1 plus the n-th divisor of 24.

2, 3, 4, 5, 7, 9, 13, 25

Offset: 1

Author

Omar E. Pol, Mar 18 2014

Keywords

• nonn
• easy
• fini
• full

Comments

Also Coxeter number (denoted m(X)) of the Niemeier lattices X whose root systems are of pure A-type according to the ADE classification; see Ono-Rolen-Trebat paper, page 3, Table 1, Pure A-type root systems.

References

• J. H. Conway and N. J. A. Sloane, "Sphere Packings, Lattices and Groups", Springer-Verlag, 3rd. ed., 1993. Table 16.1, p. 407.

Links

• Ken Ono, Larry Rolen, Sarah Trebat-Leder, Classical and umbral Moonshine: connections and p-adic properties, arXiv:1403.7312v1 [math.NT]

Crossrefs

Cf. A000521, A007240, A018253, A018623.

A subsequence of A238839.

Programs

Mathematica

1 + Divisors[24] (* Wesley Ivan Hurt, Jan 01 2024 *)

Formula

a(n) = 1 + A018253(n).