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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 13 |
| 4 | 49 |
| 5 | 190 |
| 6 | 797 |
| 7 | 3360 |
| 8 | 14534 |
| 9 | 63886 |
| 10 | 284896 |
| 11 | 1282848 |
| 12 | 5829638 |
| 13 | 26690801 |
| 14 | 122989106 |
| 15 | 569876645 |
| 16 | 2653240162 |
| 17 | 12405690763 |
| 18 | 58222972007 |
| 19 | 274173721826 |
| 20 | 1294976257690 |
| 21 | 6133081638010 |
| 22 | 29118225874467 |
| 23 | 138556467358426 |
| 24 | 660664529658206 |
| 25 | 3156133476745489 |
| 26 | 15103784291215723 |
| 27 | 72396182383167108 |
[1,1,4,13,49,190,797,3360,14534,63886,284896, 1282848,5829638,26690801,122989106,569876645, 2653240162,12405690763,58222972007,274173721826, 1294976257690,6133081638010,29118225874467, 138556467358426,660664529658206,3156133476745489, 15103784291215723,72396182383167108] |