A026031 - cp's OEIS frontend

A026031 a(n) = number of (s(0), s(1), ..., s(2n)) 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) = 7. Also a(n) = T(2n,n-2), where T is defined in A026022.

n	a(n)
2	1
3	6
4	28
5	120
6	494
7	1988
8	7888
9	31008
10	121125
11	471086
12	1826660
13	7068360
14	27313650
15	105452700
16	406923360
17	1569869760
18	6056194410
19	23366193084
20	90173331960
21	348102883184
22	1344324544156
23	5193831553416
24	20075820280544
25	77637309982400

[1, 6, 28, 120, 494, 1988, 7888, 31008, 121125, 471086, 1826660, 7068360, 27313650, 105452700, 406923360, 1569869760, 6056194410, 23366193084, 90173331960, 348102883184, 1344324544156, 5193831553416, 20075820280544, 77637309982400]

cp's OEIS Frontend

A026031 a(n) = number of (s(0), s(1), ..., s(2n)) 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) = 7. Also a(n) = T(2n,n-2), where T is defined in A026022.

Table of values

List of values