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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 2 |
| 3 | 10 |
| 4 | 50 |
| 5 | 210 |
| 6 | 882 |
| 7 | 3570 |
| 8 | 14450 |
| 9 | 57970 |
| 10 | 232562 |
| 11 | 930930 |
| 12 | 3726450 |
| 13 | 14908530 |
| 14 | 59645042 |
| 15 | 238591090 |
| 16 | 954408050 |
| 17 | 3817675890 |
| 18 | 15270878322 |
| 19 | 61083688050 |
| 20 | 244335451250 |
| 21 | 977342504050 |
| 22 | 3909372812402 |
| 23 | 15637494045810 |
| 24 | 62549987368050 |
| 25 | 250199960657010 |
| 26 | 1000799887367282 |
| 27 | 4003199594208370 |
[0,2,10,50,210,882,3570,14450,57970,232562,930930, 3726450,14908530,59645042,238591090,954408050, 3817675890,15270878322,61083688050,244335451250, 977342504050,3909372812402,15637494045810, 62549987368050,250199960657010,1000799887367282, 4003199594208370] |