156745domain: NAppears in sequencesa(n) = n^4/2-5*n^3/2+21*n-30.at n=23A217530Number of length 2+2 0..n arrays with the sum of the maximum minus the median of adjacent triples multiplied by some arrangement of +-1 equal to zero.at n=27A251936Numbers k for which A003973(k) is equal to 2*sigma(k).at n=43A337384