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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 4 |
| 3 | 9 |
| 4 | 23 |
| 5 | 66 |
| 6 | 209 |
| 7 | 722 |
| 8 | 2697 |
| 9 | 10825 |
| 10 | 46429 |
| 11 | 211799 |
| 12 | 1023304 |
| 13 | 5217048 |
| 14 | 27974458 |
| 15 | 157310519 |
| 16 | 925326848 |
| 17 | 5680341820 |
| 18 | 36315837763 |
| 19 | 241348819913 |
| 20 | 1664484383610 |
| 21 | 11893800649953 |
| 22 | 87931422125632 |
| 23 | 671699288516773 |
| 24 | 5295185052962371 |
| 25 | 43029828113547685 |
[1,2,4,9,23,66,209,722,2697,10825,46429,211799, 1023304,5217048,27974458,157310519,925326848, 5680341820,36315837763,241348819913,1664484383610, 11893800649953,87931422125632,671699288516773, 5295185052962371,43029828113547685] |