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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 13 |
| 4 | 50 |
| 5 | 179 |
| 6 | 696 |
| 7 | 2619 |
| 8 | 10119 |
| 9 | 38867 |
| 10 | 150407 |
| 11 | 582065 |
| 12 | 2260367 |
| 13 | 8786919 |
| 14 | 34225256 |
| 15 | 133471650 |
| 16 | 521216494 |
| 17 | 2037608462 |
| 18 | 7974105052 |
| 19 | 31235316275 |
| 20 | 122457794193 |
| 21 | 480473181271 |
| 22 | 1886555402750 |
| 23 | 7412471695859 |
| 24 | 29142658077266 |
| 25 | 114643347181003 |
| 26 | 451237737215201 |
[1,1,4,13,50,179,696,2619,10119,38867,150407, 582065,2260367,8786919,34225256,133471650, 521216494,2037608462,7974105052,31235316275, 122457794193,480473181271,1886555402750, 7412471695859,29142658077266,114643347181003, 451237737215201] |