A177471 - cp's OEIS frontend

A177471 Avoiding the pattern 121'2'. To avoid 121'2' means not to have four consecutive letters such that the first letter is less than the second one and the third letter is less than the fourth one.

n	a(n)
0	1
1	1
2	2
3	6
4	18
5	61
6	281
7	1541
8	8920
9	57924
10	437490
11	3611389
12	31721537
13	304085783
14	3180772870
15	35422074330
16	418050879810
17	5266547286061
18	70459362412265
19	991921937012273
20	14681437097585260
21	228615478225446360
22	3730868960721027906
23	63577641238069645741

[1, 1, 2, 6, 18, 61, 281, 1541, 8920, 57924, 437490, 3611389, 31721537, 304085783, 3180772870, 35422074330, 418050879810, 5266547286061, 70459362412265, 991921937012273, 14681437097585260, 228615478225446360, 3730868960721027906, 63577641238069645741]

cp's OEIS Frontend

A177471 Avoiding the pattern 121'2'. To avoid 121'2' means not to have four consecutive letters such that the first letter is less than the second one and the third letter is less than the fourth one.

Table of values

List of values