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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 4 |
| 3 | 18 |
| 4 | 216 |
| 5 | 1794 |
| 6 | 16050 |
| 7 | 161748 |
| 8 | 1754886 |
| 9 | 20252058 |
| 10 | 257046648 |
| 11 | 9715067802 |
| 12 | 169069882650 |
| 13 | 3334258948644 |
| 14 | 65130972856014 |
| 15 | 1314162130657122 |
| 16 | 27756075741907992 |
| 17 | 599859130159322082 |
| 18 | 13631049605170919850 |
| 19 | 318062816759187443364 |
| 20 | 7775218520916136276470 |
| 21 | 195524294317191054759258 |
| 22 | 5132224614520884668600904 |
| 23 | 139264442985628101392954898 |
[1,4,18,216,1794,16050,161748,1754886,20252058, 257046648,9715067802,169069882650,3334258948644, 65130972856014,1314162130657122,27756075741907992, 599859130159322082,13631049605170919850, 318062816759187443364,7775218520916136276470, 195524294317191054759258, 5132224614520884668600904, 139264442985628101392954898] |