| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 3 |
| 4 | 6 |
| 5 | 10 |
| 6 | 24 |
| 7 | 49 |
| 8 | 130 |
| 9 | 336 |
| 10 | 980 |
| 11 | 2904 |
| 12 | 9176 |
| 13 | 29432 |
| 14 | 97356 |
| 15 | 326399 |
| 16 | 1111770 |
| 17 | 3825238 |
| 18 | 13293456 |
| 19 | 46553116 |
| 20 | 164200028 |
| 21 | 582706692 |
| 22 | 2079517924 |
| 23 | 7458493728 |
| 24 | 26874412064 |
| 25 | 97241528200 |
| 26 | 353223728624 |
| 27 | 1287668381250 |
| 28 | 4709805627484 |
[1,2,3,6,10,24,49,130,336,980,2904,9176,29432, 97356,326399,1111770,3825238,13293456,46553116, 164200028,582706692,2079517924,7458493728, 26874412064,97241528200,353223728624, 1287668381250,4709805627484] |