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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 2 |
| 2 | 3 |
| 3 | 10 |
| 4 | 30 |
| 5 | 101 |
| 6 | 350 |
| 7 | 1250 |
| 8 | 4548 |
| 9 | 16782 |
| 10 | 62579 |
| 11 | 235273 |
| 12 | 890331 |
| 13 | 3387204 |
| 14 | 12943353 |
| 15 | 49643762 |
| 16 | 191010623 |
| 17 | 736946570 |
| 18 | 2850013623 |
| 19 | 11044973890 |
| 20 | 42882986660 |
| 21 | 166770990377 |
| 22 | 649526893537 |
| 23 | 2533096497017 |
| 24 | 9890766366030 |
| 25 | 38662031939117 |
[0,2,3,10,30,101,350,1250,4548,16782,62579,235273, 890331,3387204,12943353,49643762,191010623, 736946570,2850013623,11044973890,42882986660, 166770990377,649526893537,2533096497017, 9890766366030,38662031939117] |