4600200domain: NAppears in sequences"CHK" (necklace, identity, unlabeled) transform of 1, 2, 3, 4, ...at n=18A032170Inverse EULER transform of A064831 (with its initial 1 omitted).at n=19A072337a(n) = (1/n) * Sum_{d|n} moebius(n/d) * Lucas(d)^2, where Lucas(n) = A000204(n).at n=18A203853a(n) = A324484(n)/n.at n=18A324485