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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 4 |
| 5 | 9 |
| 6 | 23 |
| 7 | 65 |
| 8 | 199 |
| 9 | 654 |
| 10 | 2296 |
| 11 | 8569 |
| 12 | 33825 |
| 13 | 140581 |
| 14 | 612933 |
| 15 | 2795181 |
| 16 | 13298407 |
| 17 | 65851100 |
| 18 | 338654554 |
| 19 | 1805083341 |
| 20 | 9952373825 |
| 21 | 56645932971 |
| 22 | 332111798479 |
| 23 | 2000990363889 |
| 24 | 12357518954759 |
| 25 | 78010845456554 |
| 26 | 501994699807228 |
[1,1,2,4,9,23,65,199,654,2296,8569,33825,140581, 612933,2795181,13298407,65851100,338654554, 1805083341,9952373825,56645932971,332111798479, 2000990363889,12357518954759,78010845456554, 501994699807228] |