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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 3 |
| 3 | 13 |
| 4 | 65 |
| 5 | 393 |
| 6 | 2539 |
| 7 | 16866 |
| 8 | 113432 |
| 9 | 766473 |
| 10 | 5188597 |
| 11 | 35148945 |
| 12 | 238173743 |
| 13 | 1614066774 |
| 14 | 10938730576 |
| 15 | 74134306725 |
| 16 | 502428413393 |
| 17 | 3405102418833 |
| 18 | 23077383280435 |
| 19 | 156402287318610 |
| 20 | 1059984943413152 |
| 21 | 7183834447992225 |
[1,3,13,65,393,2539,16866,113432,766473,5188597, 35148945,238173743,1614066774,10938730576, 74134306725,502428413393,3405102418833, 23077383280435,156402287318610,1059984943413152, 7183834447992225] |