A056040 - cp's OEIS frontend

A056040 Swinging factorial, a(n) = 2^(n-(n mod 2))*Product_{k=1..n} k^((-1)^(k+1)).

n	a(n)
0	1
1	1
2	2
3	6
4	6
5	30
6	20
7	140
8	70
9	630
10	252
11	2772
12	924
13	12012
14	3432
15	51480
16	12870
17	218790
18	48620
19	923780
20	184756
21	3879876
22	705432
23	16224936
24	2704156
25	67603900
26	10400600
27	280816200
28	40116600
29	1163381400
30	155117520
31	4808643120
32	601080390
33	19835652870
34	2333606220

[1, 1, 2, 6, 6, 30, 20, 140, 70, 630, 252, 2772, 924, 12012, 3432, 51480, 12870, 218790, 48620, 923780, 184756, 3879876, 705432, 16224936, 2704156, 67603900, 10400600, 280816200, 40116600, 1163381400, 155117520, 4808643120, 601080390, 19835652870, 2333606220]

cp's OEIS Frontend

A056040 Swinging factorial, a(n) = 2^(n-(n mod 2))*Product_{k=1..n} k^((-1)^(k+1)).

Table of values

List of values