242137805domain: NAppears in sequencesNumber of free subsets of multiplicative group of GF(3^n).at n=17A007231Base-3 digits are, in order, the first n terms of the periodic sequence with initial period 1,2.at n=17A037480Numbers whose base-9 representation is 555555555......5.at n=9A125962a(n) = A340131(A001006(n)).at n=16A340395