A026289 - cp's OEIS frontend

A026289 a(n) = number of (s(0), s(1), ..., s(n)) such that every s(i) is an integer, s(0) = 0, s(1) = 1, s(n) = 3, |s(i) - s(i-1)| <= 1 for i >= 2, |s(2) - s(1)| = 1, |s(3) - s(2)| = 1 if s(2) = 1. Also a(n) = T(n,n-3), where T is the array in A026268.

n	a(n)
3	1
4	3
5	9
6	27
7	79
8	229
9	659
10	1889
11	5402
12	15430
13	44054
14	125786
15	359296
16	1026936
17	2937444
18	8409540
19	24097737
20	69118635
21	198442329
22	570286939
23	1640469427
24	4723363073
25	13612376671
26	39265012213
27	113358893147
28	327545797361
29	947203621523
30	2741308151929
31	7939698087777

[1, 3, 9, 27, 79, 229, 659, 1889, 5402, 15430, 44054, 125786, 359296, 1026936, 2937444, 8409540, 24097737, 69118635, 198442329, 570286939, 1640469427, 4723363073, 13612376671, 39265012213, 113358893147, 327545797361, 947203621523, 2741308151929, 7939698087777]

cp's OEIS Frontend

A026289 a(n) = number of (s(0), s(1), ..., s(n)) such that every s(i) is an integer, s(0) = 0, s(1) = 1, s(n) = 3, |s(i) - s(i-1)| <= 1 for i >= 2, |s(2) - s(1)| = 1, |s(3) - s(2)| = 1 if s(2) = 1. Also a(n) = T(n,n-3), where T is the array in A026268.

Table of values

List of values