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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 5 |
| 3 | 21 |
| 4 | 93 |
| 5 | 421 |
| 6 | 1937 |
| 7 | 9017 |
| 8 | 42349 |
| 9 | 200277 |
| 10 | 952425 |
| 11 | 4549953 |
| 12 | 21818841 |
| 13 | 104966889 |
| 14 | 506372277 |
| 15 | 2448641061 |
| 16 | 11865563853 |
| 17 | 57604036309 |
| 18 | 280110716777 |
| 19 | 1364092539041 |
| 20 | 6651682319233 |
| 21 | 32474171399649 |
| 22 | 158714415664557 |
[1,1,5,21,93,421,1937,9017,42349,200277,952425, 4549953,21818841,104966889,506372277,2448641061, 11865563853,57604036309,280110716777, 1364092539041,6651682319233,32474171399649, 158714415664557] |