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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 5 |
| 4 | 15 |
| 5 | 45 |
| 6 | 145 |
| 7 | 495 |
| 8 | 1724 |
| 9 | 6232 |
| 10 | 22887 |
| 11 | 86143 |
| 12 | 327785 |
| 13 | 1268920 |
| 14 | 4962428 |
| 15 | 19616234 |
| 16 | 78333373 |
| 17 | 315060648 |
| 18 | 1278492049 |
| 19 | 5217230819 |
| 20 | 21446008407 |
| 21 | 88584981957 |
| 22 | 368030415106 |
| 23 | 1535888895351 |
| 24 | 6438567155274 |
| 25 | 27105450435235 |
| 26 | 114519037205899 |
| 27 | 485717493848179 |
| 28 | 2066298194824836 |
[1,1,2,5,15,45,145,495,1724,6232,22887,86143, 327785,1268920,4962428,19616234,78333373, 315060648,1278492049,5217230819,21446008407, 88584981957,368030415106,1535888895351, 6438567155274,27105450435235,114519037205899, 485717493848179,2066298194824836] |