n | a(n) |
---|---|
0 | 1 |
1 | 4 |
2 | 6 |
3 | 16 |
4 | 45 |
5 | 144 |
6 | 440 |
7 | 1440 |
8 | 4680 |
9 | 15600 |
10 | 52344 |
11 | 177840 |
12 | 608160 |
13 | 2095920 |
14 | 7262640 |
15 | 25300032 |
16 | 88517520 |
17 | 310927680 |
18 | 1095923400 |
19 | 3874804560 |
20 | 13737892896 |
21 | 48829153920 |
22 | 173949483240 |
23 | 620963048160 |
24 | 2220904271040 |
25 | 7956987570576 |
26 | 28553731537320 |
27 | 102617166646800 |
[1,4,6,16,45,144,440,1440,4680,15600,52344,177840, 608160,2095920,7262640,25300032,88517520, 310927680,1095923400,3874804560,13737892896, 48829153920,173949483240,620963048160, 2220904271040,7956987570576,28553731537320, 102617166646800] |