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| n | a(n) |
|---|---|
| 1 | 4 |
| 2 | 16 |
| 3 | 50 |
| 4 | 130 |
| 5 | 296 |
| 6 | 610 |
| 7 | 1163 |
| 8 | 2083 |
| 9 | 3558 |
| 10 | 5902 |
| 11 | 9734 |
| 12 | 16410 |
| 13 | 28969 |
| 14 | 54049 |
| 15 | 105529 |
| 16 | 211097 |
| 17 | 423650 |
| 18 | 840654 |
| 19 | 1636964 |
| 20 | 3121556 |
| 21 | 5839194 |
| 22 | 10760322 |
| 23 | 19647966 |
| 24 | 35780070 |
| 25 | 65376302 |
| 26 | 120393728 |
| 27 | 223926347 |
| 28 | 420463887 |
| 29 | 795087960 |
| 30 | 1508967508 |
| 31 | 2864523898 |
[4,16,50,130,296,610,1163,2083,3558,5902,9734, 16410,28969,54049,105529,211097,423650,840654, 1636964,3121556,5839194,10760322,19647966, 35780070,65376302,120393728,223926347,420463887, 795087960,1508967508,2864523898] |