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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 4 |
| 3 | 10 |
| 4 | 37 |
| 5 | 82 |
| 6 | 352 |
| 7 | 730 |
| 8 | 2998 |
| 9 | 7291 |
| 10 | 26488 |
| 11 | 59050 |
| 12 | 263170 |
| 13 | 531442 |
| 14 | 2127952 |
| 15 | 5373460 |
| 16 | 19669879 |
| 17 | 43046722 |
| 18 | 187086916 |
| 19 | 387420490 |
| 20 | 1607136634 |
| 21 | 3878987860 |
| 22 | 13947314752 |
| 23 | 31381059610 |
| 24 | 139902374692 |
| 25 | 285916320883 |
| 26 | 1129719740248 |
| 27 | 2824682785300 |
| 28 | 10460357985970 |
[1,4,10,37,82,352,730,2998,7291,26488,59050, 263170,531442,2127952,5373460,19669879,43046722, 187086916,387420490,1607136634,3878987860, 13947314752,31381059610,139902374692,285916320883, 1129719740248,2824682785300,10460357985970] |