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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 4 |
| 2 | 26 |
| 3 | 194 |
| 4 | 1521 |
| 5 | 12289 |
| 6 | 101205 |
| 7 | 844711 |
| 8 | 7120398 |
| 9 | 60477913 |
| 10 | 516774114 |
| 11 | 4437360897 |
| 12 | 38256405777 |
| 13 | 330948944639 |
| 14 | 2871299293535 |
| 15 | 24973776734091 |
| 16 | 217690276938940 |
| 17 | 1901204163460913 |
| 18 | 16632544424086901 |
| 19 | 145730139895667887 |
| 20 | 1278596503973570665 |
| 21 | 11231908572986043199 |
[1,4,26,194,1521,12289,101205,844711,7120398, 60477913,516774114,4437360897,38256405777, 330948944639,2871299293535,24973776734091, 217690276938940,1901204163460913, 16632544424086901,145730139895667887, 1278596503973570665,11231908572986043199] |