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| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 4 |
| 3 | 11 |
| 4 | 24 |
| 5 | 41 |
| 6 | 117 |
| 7 | 278 |
| 8 | 527 |
| 9 | 1199 |
| 10 | 3116 |
| 11 | 6469 |
| 12 | 11753 |
| 13 | 33802 |
| 14 | 76443 |
| 15 | 136762 |
| 16 | 354144 |
| 17 | 873121 |
| 18 | 1721764 |
| 19 | 3565918 |
| 20 | 9653287 |
| 21 | 20783558 |
| 22 | 34867797 |
| 23 | 103232189 |
| 24 | 242017776 |
| 25 | 451910159 |
| 26 | 1064447283 |
| 27 | 2726446322 |
| 28 | 5583548873 |
| 29 | 10513816601 |
| 30 | 29729597084 |
| 31 | 66349305331 |
[2,4,11,24,41,117,278,527,1199,3116,6469,11753, 33802,76443,136762,354144,873121,1721764,3565918, 9653287,20783558,34867797,103232189,242017776, 451910159,1064447283,2726446322,5583548873, 10513816601,29729597084,66349305331] |