184637domain: NAppears in sequencesExpansion of a modular function for Gamma_0(21).at n=29A002511Number of 5-bead necklaces labeled with numbers -n..n not allowing reversal, with sum zero and first and second differences in -n..n.at n=38A209009G.f. A(x) satisfies: 1 - x = Sum_{n>=0} (x^(4*n) + (-1)^n*A(x))^n.at n=27A352820