n | a(n) |
---|---|
0 | 1 |
1 | 4 |
2 | 15 |
3 | 56 |
4 | 209 |
5 | 784 |
6 | 2958 |
7 | 11220 |
8 | 42753 |
9 | 163548 |
10 | 627770 |
11 | 2416804 |
12 | 9328384 |
13 | 36087780 |
14 | 139890764 |
15 | 543246696 |
16 | 2113015731 |
17 | 8230687548 |
18 | 32102370550 |
19 | 125358442460 |
20 | 490049744789 |
21 | 1917595810240 |
22 | 7510507532319 |
23 | 29440544167696 |
[1,4,15,56,209,784,2958,11220,42753,163548,627770, 2416804,9328384,36087780,139890764,543246696, 2113015731,8230687548,32102370550,125358442460, 490049744789,1917595810240,7510507532319, 29440544167696] |