163856domain: NAppears in sequencesTheta series of D_7 lattice.at n=21A008429Number of induced cycles in the 4 X n grid graph.at n=16A360197Numbers k such that k divides sigma(A003961(k)), where A003961 is fully multiplicative with a(p) = nextprime(p), and sigma is the sum of divisors function.at n=37A389469