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| n | a(n) |
|---|---|
| 0 | 3 |
| 1 | 16 |
| 2 | 73 |
| 3 | 316 |
| 4 | 1334 |
| 5 | 5552 |
| 6 | 22901 |
| 7 | 93892 |
| 8 | 383290 |
| 9 | 1559680 |
| 10 | 6331098 |
| 11 | 25649976 |
| 12 | 103758828 |
| 13 | 419195552 |
| 14 | 1691825933 |
| 15 | 6822051092 |
| 16 | 27488564498 |
| 17 | 110691186272 |
| 18 | 445487285678 |
| 19 | 1792047789512 |
| 20 | 7205785665908 |
| 21 | 28963557761312 |
[3,16,73,316,1334,5552,22901,93892,383290,1559680, 6331098,25649976,103758828,419195552,1691825933, 6822051092,27488564498,110691186272,445487285678, 1792047789512,7205785665908,28963557761312] |