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| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 8 |
| 3 | 20 |
| 4 | 44 |
| 5 | 116 |
| 6 | 332 |
| 7 | 900 |
| 8 | 2268 |
| 9 | 5716 |
| 10 | 14892 |
| 11 | 39268 |
| 12 | 101820 |
| 13 | 260532 |
| 14 | 668300 |
| 15 | 1727812 |
| 16 | 4469404 |
| 17 | 11506196 |
| 18 | 29540332 |
| 19 | 75933220 |
| 20 | 195497084 |
| 21 | 503093108 |
| 22 | 1292802636 |
| 23 | 3320226820 |
| 24 | 8530094940 |
| 25 | 21919963604 |
| 26 | 56309625260 |
| 27 | 144586811108 |
[2,8,20,44,116,332,900,2268,5716,14892,39268, 101820,260532,668300,1727812,4469404,11506196, 29540332,75933220,195497084,503093108,1292802636, 3320226820,8530094940,21919963604,56309625260, 144586811108] |