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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 7 |
| 4 | 30 |
| 5 | 143 |
| 6 | 728 |
| 7 | 3148 |
| 8 | 15986 |
| 9 | 86009 |
| 10 | 478907 |
| 11 | 2731365 |
| 12 | 13131703 |
| 13 | 72135374 |
| 14 | 412835191 |
| 15 | 2416852480 |
| 16 | 14369476066 |
| 17 | 72067537808 |
| 18 | 409636973141 |
| 19 | 2412844770335 |
| 20 | 14479410843183 |
| 21 | 87964452906330 |
| 22 | 451313038006432 |
[1,2,7,30,143,728,3148,15986,86009,478907,2731365, 13131703,72135374,412835191,2416852480, 14369476066,72067537808,409636973141, 2412844770335,14479410843183,87964452906330, 451313038006432] |