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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 8 |
| 4 | 60 |
| 5 | 708 |
| 6 | 11508 |
| 7 | 238356 |
| 8 | 5997924 |
| 9 | 177615460 |
| 10 | 6050014228 |
| 11 | 233010132788 |
| 12 | 10011985592516 |
| 13 | 474815000195844 |
| 14 | 24635182609510260 |
| 15 | 1388071373846060244 |
| 16 | 84406416179170495524 |
| 17 | 5509502700599270439588 |
| 18 | 384233531128293605883092 |
| 19 | 28513258202704586092168820 |
| 20 | 2243347226931600749380032388 |
| 21 | 186528883284172684793892938308 |
| 22 | 16343425532977997699916585695796 |
[1,1,2,8,60,708,11508,238356,5997924,177615460, 6050014228,233010132788,10011985592516, 474815000195844,24635182609510260, 1388071373846060244,84406416179170495524, 5509502700599270439588,384233531128293605883092, 28513258202704586092168820, 2243347226931600749380032388, 186528883284172684793892938308, 16343425532977997699916585695796] |