116277domain: NAppears in sequencesT(n,7), array T as in A050186; a count of aperiodic binary words.at n=14A051192a(n) = Sum_{d|n} d*sigma(n/d)^d.at n=20A185302Number of 2 X 2 matrices having all terms in {1,...,n} and positive determinant.at n=21A211059