A249665 - cp's OEIS frontend

A249665 The number of permutations p of {1,...,n} such that p(1)=1, p(n)=n, and |p(i)-p(i+1)| is in {1,2,3} for all i from 1 to n-1.

n	a(n)
1	1
2	1
3	1
4	2
5	6
6	14
7	28
8	56
9	118
10	254
11	541
12	1140
13	2401
14	5074
15	10738
16	22711
17	48001
18	101447
19	214446
20	453355
21	958395
22	2025963
23	4282685
24	9053286
25	19138115
26	40456779
27	85522862
28	180789396
29	382176531
30	807895636
31	1707837203
32	3610252689
33	7631830480

[1, 1, 1, 2, 6, 14, 28, 56, 118, 254, 541, 1140, 2401, 5074, 10738, 22711, 48001, 101447, 214446, 453355, 958395, 2025963, 4282685, 9053286, 19138115, 40456779, 85522862, 180789396, 382176531, 807895636, 1707837203, 3610252689, 7631830480]

cp's OEIS Frontend

A249665 The number of permutations p of {1,...,n} such that p(1)=1, p(n)=n, and |p(i)-p(i+1)| is in {1,2,3} for all i from 1 to n-1.

Table of values

List of values