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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 4 |
| 3 | 10 |
| 4 | 24 |
| 5 | 66 |
| 6 | 172 |
| 7 | 498 |
| 8 | 1360 |
| 9 | 4066 |
| 10 | 11444 |
| 11 | 34970 |
| 12 | 100520 |
| 13 | 312066 |
| 14 | 911068 |
| 15 | 2862562 |
| 16 | 8457504 |
| 17 | 26824386 |
| 18 | 80006116 |
| 19 | 255680170 |
| 20 | 768464312 |
| 21 | 2471150402 |
| 22 | 7474561164 |
| 23 | 24161357010 |
| 24 | 73473471344 |
| 25 | 238552980386 |
| 26 | 728745517972 |
[1,2,4,10,24,66,172,498,1360,4066,11444,34970, 100520,312066,911068,2862562,8457504,26824386, 80006116,255680170,768464312,2471150402, 7474561164,24161357010,73473471344,238552980386, 728745517972] |