| n | a(n) |
|---|---|
| 0 | 4 |
| 1 | 6 |
| 2 | 9 |
| 3 | 15 |
| 4 | 26 |
| 5 | 48 |
| 6 | 88 |
| 7 | 168 |
| 8 | 323 |
| 9 | 627 |
| 10 | 1225 |
| 11 | 2406 |
| 12 | 4736 |
| 13 | 9351 |
| 14 | 18504 |
| 15 | 36655 |
| 16 | 72730 |
| 17 | 144450 |
| 18 | 287147 |
| 19 | 571208 |
| 20 | 1136971 |
| 21 | 2264215 |
| 22 | 4510963 |
| 23 | 8990492 |
| 24 | 17923944 |
| 25 | 35743996 |
| 26 | 71298762 |
| 27 | 142249762 |
| 28 | 283859985 |
| 29 | 566537515 |
| 30 | 1130886504 |
| 31 | 2257704401 |
| 32 | 4507834166 |
| 33 | 9001524190 |
[4,6,9,15,26,48,88,168,323,627,1225,2406,4736, 9351,18504,36655,72730,144450,287147,571208, 1136971,2264215,4510963,8990492,17923944,35743996, 71298762,142249762,283859985,566537515,1130886504, 2257704401,4507834166,9001524190] |