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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 4 |
| 4 | 11 |
| 5 | 38 |
| 6 | 151 |
| 7 | 655 |
| 8 | 3112 |
| 9 | 16000 |
| 10 | 88285 |
| 11 | 519592 |
| 12 | 3244512 |
| 13 | 21400146 |
| 14 | 148530179 |
| 15 | 1081222613 |
| 16 | 8231314455 |
| 17 | 65369494593 |
| 18 | 540322688516 |
| 19 | 4639020151529 |
| 20 | 41295634331020 |
| 21 | 380514484523095 |
| 22 | 3623898600072459 |
| 23 | 35622399584611476 |
| 24 | 360965731323718242 |
[1,1,1,4,11,38,151,655,3112,16000,88285,519592, 3244512,21400146,148530179,1081222613,8231314455, 65369494593,540322688516,4639020151529, 41295634331020,380514484523095,3623898600072459, 35622399584611476,360965731323718242] |