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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 6 |
| 3 | 21 |
| 4 | 77 |
| 5 | 310 |
| 6 | 1308 |
| 7 | 5710 |
| 8 | 25605 |
| 9 | 117232 |
| 10 | 545719 |
| 11 | 2575126 |
| 12 | 12289906 |
| 13 | 59218913 |
| 14 | 287699288 |
| 15 | 1407690851 |
| 16 | 6930731921 |
| 17 | 34311193558 |
| 18 | 170691635544 |
| 19 | 852874403933 |
| 20 | 4278234997610 |
| 21 | 21537155141117 |
| 22 | 108771673373067 |
| 23 | 550966271295019 |
| 24 | 2798396004637028 |
| 25 | 14248670155477872 |
[1,2,6,21,77,310,1308,5710,25605,117232,545719, 2575126,12289906,59218913,287699288,1407690851, 6930731921,34311193558,170691635544,852874403933, 4278234997610,21537155141117,108771673373067, 550966271295019,2798396004637028, 14248670155477872] |