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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 10 |
| 3 | 25 |
| 4 | 66 |
| 5 | 154 |
| 6 | 360 |
| 7 | 810 |
| 8 | 1810 |
| 9 | 3982 |
| 10 | 8700 |
| 11 | 18850 |
| 12 | 40614 |
| 13 | 87030 |
| 14 | 185680 |
| 15 | 394570 |
| 16 | 835578 |
| 17 | 1763998 |
| 18 | 3713700 |
| 19 | 7798770 |
| 20 | 16340302 |
| 21 | 34166086 |
| 22 | 71303160 |
| 23 | 148548250 |
| 24 | 308980386 |
| 25 | 641728494 |
| 26 | 1330992460 |
| 27 | 2757055810 |
| 28 | 5704253430 |
[1,3,10,25,66,154,360,810,1810,3982,8700,18850, 40614,87030,185680,394570,835578,1763998,3713700, 7798770,16340302,34166086,71303160,148548250, 308980386,641728494,1330992460,2757055810, 5704253430] |