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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 6 |
| 4 | 20 |
| 5 | 55 |
| 6 | 206 |
| 7 | 654 |
| 8 | 2563 |
| 9 | 8800 |
| 10 | 35718 |
| 11 | 130207 |
| 12 | 541770 |
| 13 | 2054906 |
| 14 | 8698409 |
| 15 | 34033759 |
| 16 | 146141882 |
| 17 | 585604786 |
| 18 | 2541893678 |
| 19 | 10381735748 |
| 20 | 45477053043 |
| 21 | 188672305570 |
| 22 | 832663144479 |
| 23 | 3499532437359 |
| 24 | 15543200005075 |
| 25 | 66047435923869 |
| 26 | 294951865746390 |
| 27 | 1265127279872257 |
| 28 | 5676545403285557 |
[1,1,3,6,20,55,206,654,2563,8800,35718,130207, 541770,2054906,8698409,34033759,146141882, 585604786,2541893678,10381735748,45477053043, 188672305570,832663144479,3499532437359, 15543200005075,66047435923869,294951865746390, 1265127279872257,5676545403285557] |