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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 11 |
| 4 | 35 |
| 5 | 113 |
| 6 | 376 |
| 7 | 1276 |
| 8 | 4402 |
| 9 | 15390 |
| 10 | 54408 |
| 11 | 194169 |
| 12 | 698567 |
| 13 | 2530937 |
| 14 | 9226160 |
| 15 | 33815432 |
| 16 | 124538318 |
| 17 | 460644494 |
| 18 | 1710476504 |
| 19 | 6373775030 |
| 20 | 23826843614 |
| 21 | 89331823706 |
| 22 | 335823046544 |
| 23 | 1265571538136 |
| 24 | 4780273605460 |
| 25 | 18094046107408 |
| 26 | 68623099425856 |
| 27 | 260734318876725 |
[1,1,4,11,35,113,376,1276,4402,15390,54408,194169, 698567,2530937,9226160,33815432,124538318, 460644494,1710476504,6373775030,23826843614, 89331823706,335823046544,1265571538136, 4780273605460,18094046107408,68623099425856, 260734318876725] |