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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 5 |
| 4 | 27 |
| 5 | 169 |
| 6 | 1217 |
| 7 | 9939 |
| 8 | 90871 |
| 9 | 920069 |
| 10 | 10222989 |
| 11 | 123698167 |
| 12 | 1619321459 |
| 13 | 22805443881 |
| 14 | 343835923129 |
| 15 | 5525934478859 |
| 16 | 94309281772527 |
| 17 | 1703461402016269 |
| 18 | 32465970250192421 |
| 19 | 651123070017747999 |
| 20 | 13707854105636799979 |
[1,1,5,27,169,1217,9939,90871,920069,10222989, 123698167,1619321459,22805443881,343835923129, 5525934478859,94309281772527,1703461402016269, 32465970250192421,651123070017747999, 13707854105636799979] |