A005802 - cp's OEIS frontend

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).

n	a(n)
0	1
1	1
2	2
3	6
4	23
5	103
6	513
7	2761
8	15767
9	94359
10	586590
11	3763290
12	24792705
13	167078577
14	1148208090
15	8026793118
16	56963722223
17	409687815151
18	2981863943718
19	21937062144834
20	162958355218089
21	1221225517285209
22	9225729232653663
23	70209849031116183
24	537935616492552297

[1, 1, 2, 6, 23, 103, 513, 2761, 15767, 94359, 586590, 3763290, 24792705, 167078577, 1148208090, 8026793118, 56963722223, 409687815151, 2981863943718, 21937062144834, 162958355218089, 1221225517285209, 9225729232653663, 70209849031116183, 537935616492552297]

cp's OEIS Frontend

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).

Table of values

List of values