Number of permutations of length n which avoid the patterns 3421, 4123, 4231; or avoid the patterns 1342, 3142, 4213.

A116782

Number of permutations of length n which avoid the patterns 3421, 4123, 4231; or avoid the patterns 1342, 3142, 4213.

Terms

    a(0) =1a(1) =2a(2) =6a(3) =21a(4) =76a(5) =275a(6) =991a(7) =3563a(8) =12800a(9) =45976a(10) =165141a(11) =593184a(12) =2130737a(13) =7653715a(14) =27492557a(15) =98754742a(16) =354732286a(17) =1274217137a(18) =4577055240a(19) =16441024023a(20) =59057026159a(21) =212135955587a(22) =762003551500

External references