| n | a(n) |
|---|---|
| 1 | 4 |
| 2 | 4 |
| 3 | 16 |
| 4 | 36 |
| 5 | 94 |
| 6 | 236 |
| 7 | 602 |
| 8 | 1528 |
| 9 | 3882 |
| 10 | 9858 |
| 11 | 25038 |
| 12 | 63592 |
| 13 | 161514 |
| 14 | 410218 |
| 15 | 1041884 |
| 16 | 2646208 |
| 17 | 6720920 |
| 18 | 17069998 |
| 19 | 43354902 |
| 20 | 110114102 |
| 21 | 279671154 |
| 22 | 710317326 |
| 23 | 1804085608 |
| 24 | 4582071648 |
| 25 | 11637685314 |
| 26 | 29557748082 |
| 27 | 75071670020 |
| 28 | 190669317026 |
[4,4,16,36,94,236,602,1528,3882,9858,25038,63592, 161514,410218,1041884,2646208,6720920,17069998, 43354902,110114102,279671154,710317326,1804085608, 4582071648,11637685314,29557748082,75071670020, 190669317026] |