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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 4 |
| 4 | 12 |
| 5 | 36 |
| 6 | 121 |
| 7 | 418 |
| 8 | 1517 |
| 9 | 5671 |
| 10 | 21784 |
| 11 | 85414 |
| 12 | 341147 |
| 13 | 1383072 |
| 14 | 5681804 |
| 15 | 23605521 |
| 16 | 99049677 |
| 17 | 419246520 |
| 18 | 1788325790 |
| 19 | 7680990743 |
| 20 | 33195379744 |
| 21 | 144265731947 |
| 22 | 630155621447 |
| 23 | 2765248595670 |
| 24 | 12185699434223 |
| 25 | 53907043689333 |
| 26 | 239323911841937 |
| 27 | 1065992073492313 |
| 28 | 4762597890754407 |
[1,1,2,4,12,36,121,418,1517,5671,21784,85414, 341147,1383072,5681804,23605521,99049677, 419246520,1788325790,7680990743,33195379744, 144265731947,630155621447,2765248595670, 12185699434223,53907043689333,239323911841937, 1065992073492313,4762597890754407] |