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| n | a(n) |
|---|---|
| 1 | 4 |
| 2 | 6 |
| 3 | 12 |
| 4 | 23 |
| 5 | 43 |
| 6 | 105 |
| 7 | 233 |
| 8 | 479 |
| 9 | 968 |
| 10 | 2146 |
| 11 | 4683 |
| 12 | 9928 |
| 13 | 20709 |
| 14 | 44652 |
| 15 | 96244 |
| 16 | 205631 |
| 17 | 435063 |
| 18 | 930935 |
| 19 | 1994977 |
| 20 | 4266607 |
| 21 | 9080728 |
| 22 | 19396626 |
| 23 | 41471567 |
| 24 | 88657284 |
| 25 | 189124509 |
| 26 | 403873550 |
| 27 | 862832200 |
| 28 | 1843730503 |
| 29 | 3936307111 |
| 30 | 8406314159 |
[4,6,12,23,43,105,233,479,968,2146,4683,9928, 20709,44652,96244,205631,435063,930935,1994977, 4266607,9080728,19396626,41471567,88657284, 189124509,403873550,862832200,1843730503, 3936307111,8406314159] |