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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 6 |
| 4 | 18 |
| 5 | 50 |
| 6 | 150 |
| 7 | 492 |
| 8 | 1539 |
| 9 | 5371 |
| 10 | 17944 |
| 11 | 63704 |
| 12 | 225744 |
| 13 | 810809 |
| 14 | 2983535 |
| 15 | 10917690 |
| 16 | 40972337 |
| 17 | 153287379 |
| 18 | 581820688 |
| 19 | 2219375147 |
| 20 | 8508412508 |
| 21 | 32915586038 |
| 22 | 127540927543 |
| 23 | 498239905499 |
| 24 | 1950902335531 |
| 25 | 7679230505707 |
| 26 | 30343172222925 |
| 27 | 120261715941901 |
| 28 | 478693474593309 |
| 29 | 1909728214904899 |
[1,1,3,6,18,50,150,492,1539,5371,17944,63704, 225744,810809,2983535,10917690,40972337,153287379, 581820688,2219375147,8508412508,32915586038, 127540927543,498239905499,1950902335531, 7679230505707,30343172222925,120261715941901, 478693474593309,1909728214904899] |