28404domain: NAppears in sequencesNumber of primes less than 10000n.at n=32A038813Numbers whose set of base 13 digits is {0,C}, where C base 13 = 12 base 10.at n=13A097259Number of quadrilaterals in a triangular matchstick arrangement of side n.at n=17A204185a(n) = (6/n^3) * Sum_{d|n} moebius(n/d)*binomial(2*d,d).at n=12A268592