Number of permutations of length n which avoid the patterns 1234, 1432, 3241.

Terms

a(0) =1a(1) =2a(2) =6a(3) =21a(4) =70a(5) =199a(6) =502a(7) =1232a(8) =2962a(9) =6970a(10) =16138a(11) =36982a(12) =84083a(13) =189918a(14) =426722a(15) =954884a(16) =2129756a(17) =4737382a(18) =10514539a(19) =23294911a(20) =51533491a(21) =113864171a(22) =251330512a(23) =554292891a(24) =1221605912a(25) =2690738608a(26) =5923829534a(27) =13036444247a(28) =28679413033