99684domain: NAppears in sequences(1/2)*number of regular tetrahedra that can be formed using the points in an (n+1) X (n+1) X (n+1) lattice cube.at n=18A103158Let v = list of denominators of Farey series of order n (see A006843); a(n) = sum of products of adjacent terms of v.at n=28A278046