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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 1 |
| 6 | 1 |
| 7 | 2 |
| 8 | 6 |
| 9 | 16 |
| 10 | 59 |
| 11 | 265 |
| 12 | 1544 |
| 13 | 10778 |
| 14 | 88168 |
| 15 | 805491 |
| 16 | 8037418 |
| 17 | 86221634 |
| 18 | 985870522 |
| 19 | 11946487647 |
| 20 | 152808063181 |
| 21 | 2056692014474 |
| 22 | 29051272833609 |
| 23 | 429668180677439 |
| 24 | 6640165204855036 |
| 25 | 107026584471569605 |
| 26 | 1796101588825595008 |
| 27 | 31333997930603283531 |
| 28 | 567437240683788292989 |
[1,0,0,0,0,1,1,2,6,16,59,265,1544,10778,88168, 805491,8037418,86221634,985870522,11946487647, 152808063181,2056692014474,29051272833609, 429668180677439,6640165204855036, 107026584471569605,1796101588825595008, 31333997930603283531,567437240683788292989] |