  We show that the denominator formula for the strange series of affine
superalgebras, conjectured by Kac and Wakimoto and proved by Zagier, follows
from a classical determinant evaluation of Frobenius. As a limit case, we
obtain exact formulas for the number of representations of an arbitrary number
as a sum of 4m^2/d triangles, whenever d divides 2m, and 4m(m+1)/d triangles,
when d divides 2m or d divides 2m+2. This extends recent results of Getz and
Mahlburg, Milne, and Zagier.
