447552domain: NAppears in sequencesNumber of words of length 4 in the n(n-1)/2 transpositions of S[ n ] equivalent to the identity.at n=27A029699Number of nonequivalent ways (mod D_3) to place 4 points on an n X n X n triangular grid so that no two of them are on the same row, column or diagonal.at n=15A283115