31912

Appears in sequences

• Number of ways to place 2 nonattacking zebras on an n X n board.at n=15A172137
• Let P be a one-move "rider" with move set M={(1,2)}; a(n) is the number of non-attacking positions of two indistinguishable pieces P on an n X n board.at n=15A222308
• Numbers that are the sum of an emirp and its reversal in more than one way.at n=29A345408
• Number of unlabeled initially-finally connected digraphs with n arcs.at n=9A350906