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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 15 |
| 5 | 39 |
| 6 | 116 |
| 7 | 340 |
| 8 | 1001 |
| 9 | 3041 |
| 10 | 9322 |
| 11 | 28718 |
| 12 | 89363 |
| 13 | 279987 |
| 14 | 881376 |
| 15 | 2788464 |
| 16 | 8860677 |
| 17 | 28256709 |
| 18 | 90407666 |
| 19 | 290124182 |
| 20 | 933482527 |
| 21 | 3010689527 |
| 22 | 9731366060 |
| 23 | 31516942060 |
| 24 | 102259648701 |
| 25 | 332347297141 |
| 26 | 1081810639970 |
| 27 | 3526399820374 |
| 28 | 11510355762339 |
| 29 | 37616896717155 |
[1,1,2,6,15,39,116,340,1001,3041,9322,28718,89363, 279987,881376,2788464,8860677,28256709,90407666, 290124182,933482527,3010689527,9731366060, 31516942060,102259648701,332347297141, 1081810639970,3526399820374,11510355762339, 37616896717155] |