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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 10 |
| 4 | 34 |
| 5 | 218 |
| 6 | 1308 |
| 7 | 10596 |
| 8 | 74688 |
| 9 | 793152 |
| 10 | 7931520 |
| 11 | 94504320 |
| 12 | 1054218240 |
| 13 | 14662840320 |
| 14 | 205279764480 |
| 15 | 3427909632000 |
| 16 | 50923531008000 |
| 17 | 907545606912000 |
| 18 | 16335820924416000 |
| 19 | 323185344975360000 |
| 20 | 6220416698689536000 |
| 21 | 140360358705186816000 |
| 22 | 3087927891514109952000 |
[1,2,10,34,218,1308,10596,74688,793152,7931520, 94504320,1054218240,14662840320,205279764480, 3427909632000,50923531008000,907545606912000, 16335820924416000,323185344975360000, 6220416698689536000,140360358705186816000, 3087927891514109952000] |