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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 20 |
| 5 | 76 |
| 6 | 300 |
| 7 | 1252 |
| 8 | 5324 |
| 9 | 23124 |
| 10 | 101548 |
| 11 | 450320 |
| 12 | 2010108 |
| 13 | 9022704 |
| 14 | 40674180 |
| 15 | 184026168 |
| 16 | 835121676 |
| 17 | 3799670208 |
| 18 | 17326530900 |
| 19 | 79163726536 |
| 20 | 362316871964 |
| 21 | 1660794058176 |
| 22 | 7623209945860 |
| 23 | 35034482102360 |
| 24 | 161190157871724 |
| 25 | 742373773430192 |
| 26 | 3422236265162068 |
[1,2,6,20,76,300,1252,5324,23124,101548,450320, 2010108,9022704,40674180,184026168,835121676, 3799670208,17326530900,79163726536,362316871964, 1660794058176,7623209945860,35034482102360, 161190157871724,742373773430192,3422236265162068] |