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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 5 |
| 3 | 15 |
| 4 | 45 |
| 5 | 143 |
| 6 | 483 |
| 7 | 1644 |
| 8 | 5848 |
| 9 | 21178 |
| 10 | 77716 |
| 11 | 290588 |
| 12 | 1097869 |
| 13 | 4182986 |
| 14 | 16151078 |
| 15 | 62672479 |
| 16 | 245500460 |
| 17 | 967557537 |
| 18 | 3835676351 |
| 19 | 15285272154 |
| 20 | 61245921696 |
| 21 | 246253276079 |
| 22 | 995260779078 |
| 23 | 4034182783045 |
| 24 | 16419400425310 |
| 25 | 67016453054374 |
| 26 | 274452294823460 |
| 27 | 1126645933307878 |
| 28 | 4639258411263086 |
[1,2,5,15,45,143,483,1644,5848,21178,77716,290588, 1097869,4182986,16151078,62672479,245500460, 967557537,3835676351,15285272154,61245921696, 246253276079,995260779078,4034182783045, 16419400425310,67016453054374,274452294823460, 1126645933307878,4639258411263086] |