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| n | a(n) |
|---|---|
| 1 | 4 |
| 2 | 15 |
| 3 | 50 |
| 4 | 176 |
| 5 | 614 |
| 6 | 2141 |
| 7 | 7472 |
| 8 | 26070 |
| 9 | 90964 |
| 10 | 317393 |
| 11 | 1107448 |
| 12 | 3864117 |
| 13 | 13482703 |
| 14 | 47043939 |
| 15 | 164146038 |
| 16 | 572739484 |
| 17 | 1998406551 |
| 18 | 6972853897 |
| 19 | 24329729820 |
| 20 | 84891460788 |
| 21 | 296203869417 |
| 22 | 1033516580387 |
| 23 | 3606153167543 |
| 24 | 12582614458784 |
[4,15,50,176,614,2141,7472,26070,90964,317393, 1107448,3864117,13482703,47043939,164146038, 572739484,1998406551,6972853897,24329729820, 84891460788,296203869417,1033516580387, 3606153167543,12582614458784] |