A038718 - cp's OEIS frontend

A038718 Number of permutations P of {1,2,...,n} such that P(1)=1 and |P^-1(i+1)-P^-1(i)| equals 1 or 2 for i=1,2,...,n-1.

n	a(n)
1	1
2	1
3	2
4	4
5	6
6	9
7	14
8	21
9	31
10	46
11	68
12	100
13	147
14	216
15	317
16	465
17	682
18	1000
19	1466
20	2149
21	3150
22	4617
23	6767
24	9918
25	14536
26	21304
27	31223
28	45760
29	67065
30	98289
31	144050
32	211116
33	309406
34	453457
35	664574
36	973981
37	1427439
38	2092014
39	3065996
40	4493436
41	6585451

[1, 1, 2, 4, 6, 9, 14, 21, 31, 46, 68, 100, 147, 216, 317, 465, 682, 1000, 1466, 2149, 3150, 4617, 6767, 9918, 14536, 21304, 31223, 45760, 67065, 98289, 144050, 211116, 309406, 453457, 664574, 973981, 1427439, 2092014, 3065996, 4493436, 6585451]

cp's OEIS Frontend

A038718 Number of permutations P of {1,2,...,n} such that P(1)=1 and |P^-1(i+1)-P^-1(i)| equals 1 or 2 for i=1,2,...,n-1.

Table of values

List of values