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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 7 |
| 3 | 24 |
| 4 | 102 |
| 5 | 408 |
| 6 | 1780 |
| 7 | 7757 |
| 8 | 34690 |
| 9 | 156181 |
| 10 | 714290 |
| 11 | 3284745 |
| 12 | 15233382 |
| 13 | 71023292 |
| 14 | 333095347 |
| 15 | 1568553797 |
| 16 | 7414909448 |
| 17 | 35181429040 |
| 18 | 167431337614 |
| 19 | 798833158181 |
| 20 | 3821411069783 |
| 21 | 18320729388070 |
| 22 | 88002183243400 |
| 23 | 423509713884975 |
| 24 | 2041556485188807 |
| 25 | 9856228838965220 |
| 26 | 47651583418203953 |
| 27 | 230679383659481441 |
[1,2,7,24,102,408,1780,7757,34690,156181,714290, 3284745,15233382,71023292,333095347,1568553797, 7414909448,35181429040,167431337614,798833158181, 3821411069783,18320729388070,88002183243400, 423509713884975,2041556485188807,9856228838965220, 47651583418203953,230679383659481441] |