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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 1 |
| 3 | 4 |
| 4 | 12 |
| 5 | 34 |
| 6 | 92 |
| 7 | 242 |
| 8 | 628 |
| 9 | 1616 |
| 10 | 4138 |
| 11 | 10570 |
| 12 | 26970 |
| 13 | 68798 |
| 14 | 175545 |
| 15 | 448176 |
| 16 | 1145058 |
| 17 | 2927924 |
| 18 | 7493021 |
| 19 | 19191836 |
| 20 | 49195806 |
| 21 | 126205062 |
| 22 | 324000494 |
| 23 | 832371414 |
| 24 | 2139802870 |
| 25 | 5504256592 |
| 26 | 14166936063 |
| 27 | 36483006046 |
| 28 | 94000206216 |
[0,1,4,12,34,92,242,628,1616,4138,10570,26970, 68798,175545,448176,1145058,2927924,7493021, 19191836,49195806,126205062,324000494,832371414, 2139802870,5504256592,14166936063,36483006046, 94000206216] |