Number of permutations of [n] avoiding {1324, 2341, 4123}.

Terms

a(0) =1a(1) =1a(2) =2a(3) =6a(4) =21a(5) =72a(6) =230a(7) =701a(8) =2113a(9) =6475a(10) =20468a(11) =66969a(12) =226027a(13) =782276a(14) =2760094a(15) =9880455a(16) =35758457a(17) =130507165a(18) =479487736a(19) =1771213935a(20) =6572533275a(21) =24484124014a(22) =91520352034a(23) =343139355270