Number of permutations in S_n with longest increasing subsequence of length <= 3 (i.e., 1234-avoiding permutations); vexillary permutations (i.e., 2143-avoiding).
A005802
Number of permutations in S_n with longest increasing subsequence of length <= 3 (i.e., 1234-avoiding permutations); vexillary permutations (i.e., 2143-avoiding).
Terms
- a(0) =1a(1) =1a(2) =2a(3) =6a(4) =23a(5) =103a(6) =513a(7) =2761a(8) =15767a(9) =94359a(10) =586590a(11) =3763290a(12) =24792705a(13) =167078577a(14) =1148208090a(15) =8026793118a(16) =56963722223a(17) =409687815151
External references
- oeis: A005802