A001909 - cp's OEIS frontend

A001909 a(n) = na(n-1) + (n-4)a(n-2), a(2) = 0, a(3) = 1.

n	a(n)
2	0
3	1
4	4
5	21
6	134
7	1001
8	8544
9	81901
10	870274
11	10146321
12	128718044
13	1764651461
14	25992300894
15	409295679481
16	6860638482424
17	121951698034461
18	2291179503374234
19	45361686034627361
20	943892592746534964
21	20592893110265899381
22	470033715095287415734

[0, 1, 4, 21, 134, 1001, 8544, 81901, 870274, 10146321, 128718044, 1764651461, 25992300894, 409295679481, 6860638482424, 121951698034461, 2291179503374234, 45361686034627361, 943892592746534964, 20592893110265899381, 470033715095287415734]

cp's OEIS Frontend

A001909 a(n) = na(n-1) + (n-4)a(n-2), a(2) = 0, a(3) = 1.

Table of values

List of values

cp's OEIS Frontend

A001909 a(n) = n*a(n-1) + (n-4)*a(n-2), a(2) = 0, a(3) = 1.

Table of values

List of values

A001909 a(n) = na(n-1) + (n-4)a(n-2), a(2) = 0, a(3) = 1.