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| n | a(n) |
|---|---|
| 3 | 0 |
| 4 | 0 |
| 5 | 4 |
| 6 | 6 |
| 7 | 4 |
| 8 | 16 |
| 9 | 60 |
| 10 | 88 |
| 11 | 224 |
| 12 | 650 |
| 13 | 1480 |
| 14 | 3372 |
| 15 | 9208 |
| 16 | 23126 |
| 17 | 56988 |
| 18 | 147778 |
| 19 | 387084 |
| 20 | 998552 |
| 21 | 2604672 |
| 22 | 6890844 |
| 23 | 18189156 |
| 24 | 48123802 |
| 25 | 128110692 |
| 26 | 341753792 |
| 27 | 912635960 |
| 28 | 2443846624 |
| 29 | 6557775236 |
| 30 | 17619900692 |
| 31 | 47420051376 |
[0,0,4,6,4,16,60,88,224,650,1480,3372,9208,23126, 56988,147778,387084,998552,2604672,6890844, 18189156,48123802,128110692,341753792,912635960, 2443846624,6557775236,17619900692,47420051376] |