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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 11 |
| 4 | 42 |
| 5 | 174 |
| 6 | 763 |
| 7 | 3457 |
| 8 | 16075 |
| 9 | 76351 |
| 10 | 368767 |
| 11 | 1805682 |
| 12 | 8943948 |
| 13 | 44736096 |
| 14 | 225646033 |
| 15 | 1146461185 |
| 16 | 5862224756 |
| 17 | 30144922281 |
| 18 | 155791900727 |
| 19 | 808773877919 |
| 20 | 4215675455503 |
| 21 | 22054576750972 |
| 22 | 115765182718467 |
| 23 | 609508331610920 |
| 24 | 3218059655553030 |
| 25 | 17034314889643633 |
[1,1,3,11,42,174,763,3457,16075,76351,368767, 1805682,8943948,44736096,225646033,1146461185, 5862224756,30144922281,155791900727,808773877919, 4215675455503,22054576750972,115765182718467, 609508331610920,3218059655553030, 17034314889643633] |