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| n | a(n) |
|---|---|
| 2 | 1 |
| 3 | 7 |
| 4 | 37 |
| 5 | 178 |
| 6 | 825 |
| 7 | 3774 |
| 8 | 17250 |
| 9 | 79326 |
| 10 | 368516 |
| 11 | 1733597 |
| 12 | 8268603 |
| 13 | 40003178 |
| 14 | 196273837 |
| 15 | 976066486 |
| 16 | 4915503146 |
| 17 | 25042730042 |
| 18 | 128927697340 |
| 19 | 670023585820 |
| 20 | 3511276691660 |
| 21 | 18537816521102 |
| 22 | 98514404946264 |
| 23 | 526575421631986 |
[1,7,37,178,825,3774,17250,79326,368516,1733597, 8268603,40003178,196273837,976066486,4915503146, 25042730042,128927697340,670023585820, 3511276691660,18537816521102,98514404946264, 526575421631986] |