n | a(n) |
---|---|
0 | 1 |
1 | 4 |
2 | 21 |
3 | 120 |
4 | 715 |
5 | 4368 |
6 | 27132 |
7 | 170544 |
8 | 1081575 |
9 | 6906900 |
10 | 44352165 |
11 | 286097760 |
12 | 1852482996 |
13 | 12033222880 |
14 | 78378960360 |
15 | 511738760544 |
16 | 3348108992991 |
17 | 21945588357420 |
18 | 144079707346575 |
19 | 947309492837400 |
20 | 6236646703759395 |
[1,4,21,120,715,4368,27132,170544,1081575,6906900, 44352165,286097760,1852482996,12033222880, 78378960360,511738760544,3348108992991, 21945588357420,144079707346575,947309492837400, 6236646703759395] |