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| n | a(n) |
|---|---|
| 1 | 4 |
| 2 | 16 |
| 3 | 50 |
| 4 | 130 |
| 5 | 296 |
| 6 | 610 |
| 7 | 1177 |
| 8 | 2209 |
| 9 | 4202 |
| 10 | 8366 |
| 11 | 17569 |
| 12 | 38251 |
| 13 | 84134 |
| 14 | 183334 |
| 15 | 392284 |
| 16 | 824110 |
| 17 | 1708779 |
| 18 | 3523509 |
| 19 | 7276452 |
| 20 | 15117730 |
| 21 | 31635969 |
| 22 | 66571659 |
| 23 | 140445543 |
| 24 | 296202061 |
| 25 | 623355780 |
| 26 | 1308333724 |
| 27 | 2740013491 |
| 28 | 5731815041 |
| 29 | 11989696656 |
[4,16,50,130,296,610,1177,2209,4202,8366,17569, 38251,84134,183334,392284,824110,1708779,3523509, 7276452,15117730,31635969,66571659,140445543, 296202061,623355780,1308333724,2740013491, 5731815041,11989696656] |