A026026 - cp's OEIS frontend

A026026 a(n) = number of (s(0), s(1), ..., s(2n-1)) such that s(i) is a nonnegative integer and |s(i) - s(i-1)| = 1 for i = 1,2,...,n, s(0) = 3, s(2n-1) = 4. Also a(n) = T(2n-1,n-1), where T is defined in A026022.

n	a(n)
2	1
3	3
4	10
5	35
6	125
7	451
8	1638
9	5980
10	21930
11	80750
12	298452
13	1106921
14	4118725
15	15371475
16	57528750
17	215867880
18	811985790
19	3061229850
20	11565545100
21	43782423750
22	166051490514
23	630877833102
24	2400830868860
25	9150602070760
26	34927775872500
27	133502608167292

[1, 3, 10, 35, 125, 451, 1638, 5980, 21930, 80750, 298452, 1106921, 4118725, 15371475, 57528750, 215867880, 811985790, 3061229850, 11565545100, 43782423750, 166051490514, 630877833102, 2400830868860, 9150602070760, 34927775872500, 133502608167292]

cp's OEIS Frontend

A026026 a(n) = number of (s(0), s(1), ..., s(2n-1)) such that s(i) is a nonnegative integer and |s(i) - s(i-1)| = 1 for i = 1,2,...,n, s(0) = 3, s(2n-1) = 4. Also a(n) = T(2n-1,n-1), where T is defined in A026022.

Table of values

List of values