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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 1 |
| 3 | 5 |
| 4 | 15 |
| 5 | 56 |
| 6 | 203 |
| 7 | 757 |
| 8 | 2839 |
| 9 | 10736 |
| 10 | 40821 |
| 11 | 155948 |
| 12 | 598065 |
| 13 | 2301118 |
| 14 | 8878591 |
| 15 | 34340085 |
| 16 | 133100055 |
| 17 | 516851528 |
| 18 | 2010358061 |
| 19 | 7831136920 |
| 20 | 30546063745 |
| 21 | 119291436738 |
| 22 | 466379022561 |
| 23 | 1825168170620 |
| 24 | 7149316835465 |
| 25 | 28027993191706 |
| 26 | 109965636641173 |
[0,1,1,5,15,56,203,757,2839,10736,40821,155948, 598065,2301118,8878591,34340085,133100055, 516851528,2010358061,7831136920,30546063745, 119291436738,466379022561,1825168170620, 7149316835465,28027993191706,109965636641173] |