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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 7 |
| 4 | 30 |
| 5 | 69 |
| 6 | 305 |
| 7 | 821 |
| 8 | 3706 |
| 9 | 10951 |
| 10 | 50167 |
| 11 | 157879 |
| 12 | 731126 |
| 13 | 2409735 |
| 14 | 11251900 |
| 15 | 38416059 |
| 16 | 180553280 |
| 17 | 633903339 |
| 18 | 2995076713 |
| 19 | 10757081251 |
| 20 | 51047312394 |
| 21 | 186835993771 |
| 22 | 889875336356 |
| 23 | 3309417001979 |
| 24 | 15811570006020 |
| 25 | 59613630920579 |
| 26 | 285586423605813 |
| 27 | 1089612947988583 |
| 28 | 5232179206138834 |
[1,1,4,7,30,69,305,821,3706,10951,50167,157879, 731126,2409735,11251900,38416059,180553280, 633903339,2995076713,10757081251,51047312394, 186835993771,889875336356,3309417001979, 15811570006020,59613630920579,285586423605813, 1089612947988583,5232179206138834] |