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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 8 |
| 4 | 21 |
| 5 | 52 |
| 6 | 132 |
| 7 | 313 |
| 8 | 741 |
| 9 | 1684 |
| 10 | 3711 |
| 11 | 7895 |
| 12 | 16310 |
| 13 | 32604 |
| 14 | 63363 |
| 15 | 119745 |
| 16 | 220546 |
| 17 | 396428 |
| 18 | 696750 |
| 19 | 1198812 |
| 20 | 2022503 |
| 21 | 3349574 |
| 22 | 5452496 |
| 23 | 8732932 |
| 24 | 13776366 |
| 25 | 21423968 |
| 26 | 32872642 |
| 27 | 49804323 |
| 28 | 74560913 |
| 29 | 110369469 |
| 30 | 161639227 |
[1,1,3,8,21,52,132,313,741,1684,3711,7895,16310, 32604,63363,119745,220546,396428,696750,1198812, 2022503,3349574,5452496,8732932,13776366,21423968, 32872642,49804323,74560913,110369469,161639227] |