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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 19 |
| 5 | 64 |
| 6 | 225 |
| 7 | 816 |
| 8 | 3031 |
| 9 | 11473 |
| 10 | 44096 |
| 11 | 171631 |
| 12 | 675130 |
| 13 | 2679728 |
| 14 | 10719237 |
| 15 | 43168826 |
| 16 | 174885089 |
| 17 | 712222799 |
| 18 | 2914150406 |
| 19 | 11973792218 |
| 20 | 49385167369 |
| 21 | 204386777160 |
| 22 | 848530495383 |
| 23 | 3532844222611 |
| 24 | 14747626307436 |
| 25 | 61712139464939 |
[1,1,2,6,19,64,225,816,3031,11473,44096,171631, 675130,2679728,10719237,43168826,174885089, 712222799,2914150406,11973792218,49385167369, 204386777160,848530495383,3532844222611, 14747626307436,61712139464939] |