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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 12 |
| 3 | 41 |
| 4 | 164 |
| 5 | 590 |
| 6 | 2360 |
| 7 | 8715 |
| 8 | 34860 |
| 9 | 130776 |
| 10 | 523104 |
| 11 | 1983212 |
| 12 | 7932848 |
| 13 | 30303416 |
| 14 | 121213664 |
| 15 | 465673065 |
| 16 | 1862692260 |
| 17 | 7187760140 |
| 18 | 28751040560 |
| 19 | 111338982436 |
| 20 | 445355929744 |
| 21 | 1729672999418 |
| 22 | 6918691997672 |
| 23 | 26936111629934 |
| 24 | 107744446519736 |
| 25 | 420338301077100 |
[1,3,12,41,164,590,2360,8715,34860,130776,523104, 1983212,7932848,30303416,121213664,465673065, 1862692260,7187760140,28751040560,111338982436, 445355929744,1729672999418,6918691997672, 26936111629934,107744446519736,420338301077100] |