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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 4 |
| 4 | 8 |
| 5 | 23 |
| 6 | 88 |
| 7 | 379 |
| 8 | 3044 |
| 9 | 32116 |
| 10 | 379279 |
| 11 | 9160509 |
| 12 | 237458908 |
| 13 | 7651718328 |
| 14 | 495105710770 |
| 15 | 29747390685988 |
| 16 | 2718143583980173 |
| 17 | 436044028162542425 |
| 18 | 61494671526637653928 |
| 19 | 16346049663440380567782 |
| 20 | 6106008029903796482509688 |
[1,1,2,4,8,23,88,379,3044,32116,379279,9160509, 237458908,7651718328,495105710770,29747390685988, 2718143583980173,436044028162542425, 61494671526637653928,16346049663440380567782, 6106008029903796482509688] |