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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 5 |
| 3 | 18 |
| 4 | 65 |
| 5 | 218 |
| 6 | 693 |
| 7 | 2138 |
| 8 | 6497 |
| 9 | 19602 |
| 10 | 58949 |
| 11 | 177026 |
| 12 | 531297 |
| 13 | 1594154 |
| 14 | 4782773 |
| 15 | 14348682 |
| 16 | 43046465 |
| 17 | 129139874 |
| 18 | 387420165 |
| 19 | 1162261106 |
| 20 | 3486784001 |
| 21 | 10460352762 |
| 22 | 31381059125 |
| 23 | 94143178298 |
| 24 | 282429535905 |
| 25 | 847288608818 |
[1,2,5,18,65,218,693,2138,6497,19602,58949,177026, 531297,1594154,4782773,14348682,43046465, 129139874,387420165,1162261106,3486784001, 10460352762,31381059125,94143178298,282429535905, 847288608818] |