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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 2 |
| 2 | 12 |
| 3 | 50 |
| 4 | 204 |
| 5 | 818 |
| 6 | 3276 |
| 7 | 13106 |
| 8 | 52428 |
| 9 | 209714 |
| 10 | 838860 |
| 11 | 3355442 |
| 12 | 13421772 |
| 13 | 53687090 |
| 14 | 214748364 |
| 15 | 858993458 |
| 16 | 3435973836 |
| 17 | 13743895346 |
| 18 | 54975581388 |
| 19 | 219902325554 |
| 20 | 879609302220 |
| 21 | 3518437208882 |
| 22 | 14073748835532 |
| 23 | 56294995342130 |
| 24 | 225179981368524 |
| 25 | 900719925474098 |
[0,2,12,50,204,818,3276,13106,52428,209714,838860, 3355442,13421772,53687090,214748364,858993458, 3435973836,13743895346,54975581388,219902325554, 879609302220,3518437208882,14073748835532, 56294995342130,225179981368524,900719925474098] |