A026017 - cp's OEIS frontend

A026017 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) = 2, s(2n-1) = 5. Also a(n) = T(2n-1,n-2), where T is the array defined in A026009.

n	a(n)
2	1
3	5
4	21
5	83
6	319
7	1209
8	4550
9	17068
10	63954
11	239666
12	898909
13	3375825
14	12697035
15	47833905
16	180510210
17	682341000
18	2583591150
19	9798281910
20	37218303330
21	141585223494
22	539395269462
23	2057771255210
24	7860697923436
25	30065829471048
26	115135255095140
27	441410428339972

[1, 5, 21, 83, 319, 1209, 4550, 17068, 63954, 239666, 898909, 3375825, 12697035, 47833905, 180510210, 682341000, 2583591150, 9798281910, 37218303330, 141585223494, 539395269462, 2057771255210, 7860697923436, 30065829471048, 115135255095140, 441410428339972]

cp's OEIS Frontend

A026017 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) = 2, s(2n-1) = 5. Also a(n) = T(2n-1,n-2), where T is the array defined in A026009.

Table of values

List of values