A026109 - cp's OEIS frontend

A026109 a(n) = number of (s(0), s(1), ..., s(n)) such that every s(i) is a nonnegative integer, s(0) = 0, s(1) = 1, s(n) = 3, |s(i) - s(i-1)| <= 1 for i >= 2. Also a(n) = T(n,n-3), where T is the array defined in A026105.

n	a(n)
3	1
4	3
5	10
6	30
7	89
8	259
9	748
10	2148
11	6150
12	17578
13	50204
14	143364
15	409500
16	1170300
17	3346944
18	9579840
19	27444681
20	78698475
21	225887010
22	648985414
23	1866356437
24	5372348487
25	15478733108
26	44637360700
27	128837626255
28	372183158061
29	1076041247778

[1, 3, 10, 30, 89, 259, 748, 2148, 6150, 17578, 50204, 143364, 409500, 1170300, 3346944, 9579840, 27444681, 78698475, 225887010, 648985414, 1866356437, 5372348487, 15478733108, 44637360700, 128837626255, 372183158061, 1076041247778]

cp's OEIS Frontend

A026109 a(n) = number of (s(0), s(1), ..., s(n)) such that every s(i) is a nonnegative integer, s(0) = 0, s(1) = 1, s(n) = 3, |s(i) - s(i-1)| <= 1 for i >= 2. Also a(n) = T(n,n-3), where T is the array defined in A026105.

Table of values

List of values