90876domain: NAppears in sequencesa(n) = Sum_{d|n} A007955(d) * A008683(n/d) = Sum_{d|n} A007955(d) * mu(n/d), where A007955(m) = number of divisors of m.at n=44A174940Number of (w,x,y,z) with all terms in {1,...,n} and 2|w-x|<n+|y-z|.at n=18A212687