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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 4 |
| 3 | 12 |
| 4 | 41 |
| 5 | 131 |
| 6 | 458 |
| 7 | 1574 |
| 8 | 5664 |
| 9 | 20766 |
| 10 | 78647 |
| 11 | 306438 |
| 12 | 1233636 |
| 13 | 5127670 |
| 14 | 22036940 |
| 15 | 97905965 |
| 16 | 449634928 |
| 17 | 2133165981 |
| 18 | 10445593354 |
| 19 | 52735714850 |
| 20 | 274162571129 |
| 21 | 1465821995582 |
| 22 | 8049360711049 |
| 23 | 45342104688820 |
| 24 | 261687650813517 |
[1,4,12,41,131,458,1574,5664,20766,78647,306438, 1233636,5127670,22036940,97905965,449634928, 2133165981,10445593354,52735714850,274162571129, 1465821995582,8049360711049,45342104688820, 261687650813517] |