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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 5 |
| 5 | 13 |
| 6 | 40 |
| 7 | 126 |
| 8 | 409 |
| 9 | 1360 |
| 10 | 4611 |
| 11 | 15878 |
| 12 | 55384 |
| 13 | 195282 |
| 14 | 694910 |
| 15 | 2492454 |
| 16 | 9001405 |
| 17 | 32704855 |
| 18 | 119462142 |
| 19 | 438441266 |
| 20 | 1616001547 |
| 21 | 5979144981 |
| 22 | 22199682130 |
| 23 | 82685478702 |
| 24 | 308864831632 |
| 25 | 1156806962608 |
| 26 | 4343254831180 |
| 27 | 16343719170558 |
| 28 | 61630500821158 |
| 29 | 232854921227616 |
| 30 | 881378279895534 |
[1,1,2,5,13,40,126,409,1360,4611,15878,55384, 195282,694910,2492454,9001405,32704855,119462142, 438441266,1616001547,5979144981,22199682130, 82685478702,308864831632,1156806962608, 4343254831180,16343719170558,61630500821158, 232854921227616,881378279895534] |