A004981 - cp's OEIS frontend

A004981 a(n) = (2^n/n!) * Product_{k=0..n-1} (4*k + 1).

n	a(n)
0	1
1	2
2	10
3	60
4	390
5	2652
6	18564
7	132600
8	961350
9	7049900
10	52169260
11	388898120
12	2916735900
13	21987701400
14	166478310600
15	1265235160560
16	9647418099270
17	73774373700300
18	565603531702300
19	4346216612028200
20	33465867912617140
21	258165266754475080
22	1994913424920943800

[1, 2, 10, 60, 390, 2652, 18564, 132600, 961350, 7049900, 52169260, 388898120, 2916735900, 21987701400, 166478310600, 1265235160560, 9647418099270, 73774373700300, 565603531702300, 4346216612028200, 33465867912617140, 258165266754475080, 1994913424920943800]

cp's OEIS Frontend

A004981 a(n) = (2^n/n!) * Product_{k=0..n-1} (4*k + 1).

Table of values

List of values