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| n | a(n) |
|---|---|
| 2 | 1 |
| 3 | 3 |
| 4 | 7 |
| 5 | 18 |
| 6 | 46 |
| 7 | 120 |
| 8 | 316 |
| 9 | 841 |
| 10 | 2257 |
| 11 | 6103 |
| 12 | 16611 |
| 13 | 45475 |
| 14 | 125139 |
| 15 | 345957 |
| 16 | 960417 |
| 17 | 2676291 |
| 18 | 7483299 |
| 19 | 20989833 |
| 20 | 59042805 |
| 21 | 166520124 |
| 22 | 470781528 |
| 23 | 1333970190 |
| 24 | 3787707322 |
| 25 | 10775741271 |
| 26 | 30711538351 |
| 27 | 87677551081 |
| 28 | 250704001213 |
| 29 | 717923179762 |
[1,3,7,18,46,120,316,841,2257,6103,16611,45475, 125139,345957,960417,2676291,7483299,20989833, 59042805,166520124,470781528,1333970190, 3787707322,10775741271,30711538351,87677551081, 250704001213,717923179762] |