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| n | a(n) |
|---|---|
| 0 | 4 |
| 1 | 15 |
| 2 | 60 |
| 3 | 239 |
| 4 | 952 |
| 5 | 3792 |
| 6 | 15104 |
| 7 | 60161 |
| 8 | 239628 |
| 9 | 954465 |
| 10 | 3801740 |
| 11 | 15142752 |
| 12 | 60315260 |
| 13 | 240242367 |
| 14 | 956911980 |
| 15 | 3811486495 |
| 16 | 15181573232 |
| 17 | 60469889136 |
| 18 | 240858271816 |
| 19 | 959365196977 |
| 20 | 3821257929948 |
| 21 | 15220493940369 |
| 22 | 60624914631700 |
| 23 | 241475755550400 |
| 24 | 961824703141876 |
[4,15,60,239,952,3792,15104,60161,239628,954465, 3801740,15142752,60315260,240242367,956911980, 3811486495,15181573232,60469889136,240858271816, 959365196977,3821257929948,15220493940369, 60624914631700,241475755550400,961824703141876] |