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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 5 |
| 4 | 15 |
| 5 | 52 |
| 6 | 201 |
| 7 | 847 |
| 8 | 3836 |
| 9 | 18489 |
| 10 | 94153 |
| 11 | 503775 |
| 12 | 2819947 |
| 13 | 16456748 |
| 14 | 99843685 |
| 15 | 628285253 |
| 16 | 4092639203 |
| 17 | 27551233223 |
| 18 | 191405419444 |
| 19 | 1370602542782 |
| 20 | 10105310949388 |
| 21 | 76641003455357 |
| 22 | 597426261051281 |
| 23 | 4782940241616478 |
| 24 | 39300668695536996 |
| 25 | 331231384805916410 |
[1,1,2,5,15,52,201,847,3836,18489,94153,503775, 2819947,16456748,99843685,628285253,4092639203, 27551233223,191405419444,1370602542782, 10105310949388,76641003455357,597426261051281, 4782940241616478,39300668695536996, 331231384805916410] |