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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 13 |
| 4 | 55 |
| 5 | 236 |
| 6 | 1035 |
| 7 | 4593 |
| 8 | 20551 |
| 9 | 92578 |
| 10 | 419338 |
| 11 | 1907951 |
| 12 | 8713555 |
| 13 | 39921038 |
| 14 | 183396671 |
| 15 | 844515563 |
| 16 | 3896933367 |
| 17 | 18014916576 |
| 18 | 83415684654 |
| 19 | 386807933378 |
| 20 | 1796024496430 |
| 21 | 8349190182990 |
| 22 | 38854827380075 |
| 23 | 180997895984903 |
| 24 | 843906670596499 |
| 25 | 3938005827167461 |
| 26 | 18390418912425940 |
[1,1,3,13,55,236,1035,4593,20551,92578,419338, 1907951,8713555,39921038,183396671,844515563, 3896933367,18014916576,83415684654,386807933378, 1796024496430,8349190182990,38854827380075, 180997895984903,843906670596499,3938005827167461, 18390418912425940] |