4968057848domain: NAppears in sequencesNumber of ways of placing n nonattacking queens on an n X n board.at n=19A000170Erroneous duplicate of A000170, see comments.at n=18A140393Number of solutions to the n-queens puzzle in a n X n board that are not square root permutations of {n-1,...,2,1,0}.at n=18A383738