137304735744domain: NAppears in sequencesa(n) = 8^(n-1)*(2^n - 1).at n=9A060195Number of Pythagorean triples mod 2^n; i.e., number of solutions to x^2 + y^2 = z^2 mod 2^n.at n=18A091143a(n) = Sum_{d|n} Moebius(n/d)*d^(b-1)/phi(n) for b = 11.at n=15A160957