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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 22 |
| 2 | 142 |
| 3 | 730 |
| 4 | 4390 |
| 5 | 26742 |
| 6 | 166966 |
| 7 | 1056350 |
| 8 | 6755686 |
| 9 | 43557742 |
| 10 | 282683662 |
| 11 | 1844363158 |
| 12 | 12086792278 |
| 13 | 79504493454 |
| 14 | 524626264542 |
| 15 | 3471321731070 |
| 16 | 23023441009542 |
| 17 | 153019621221454 |
| 18 | 1018866986428048 |
| 19 | 6795005681508340 |
[1,22,142,730,4390,26742,166966,1056350,6755686, 43557742,282683662,1844363158,12086792278, 79504493454,524626264542,3471321731070, 23023441009542,153019621221454,1018866986428048, 6795005681508340] |