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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 6 |
| 3 | 12 |
| 4 | 26 |
| 5 | 48 |
| 6 | 118 |
| 7 | 132 |
| 8 | 98 |
| 9 | 880 |
| 10 | 1590 |
| 11 | 3332 |
| 12 | 6370 |
| 13 | 13552 |
| 14 | 24886 |
| 15 | 50180 |
| 16 | 98786 |
| 17 | 221808 |
| 18 | 442422 |
| 19 | 891396 |
| 20 | 1782242 |
| 21 | 3670000 |
| 22 | 6944822 |
| 23 | 13063940 |
| 24 | 29101282 |
| 25 | 55208304 |
| 26 | 100895798 |
| 27 | 228823556 |
| 28 | 419893730 |
| 29 | 820973552 |
| 30 | 2089735222 |
| 31 | 2685666052 |
| 32 | 738308322 |
| 33 | 13404695920 |
[1,0,6,12,26,48,118,132,98,880,1590,3332,6370, 13552,24886,50180,98786,221808,442422,891396, 1782242,3670000,6944822,13063940,29101282, 55208304,100895798,228823556,419893730,820973552, 2089735222,2685666052,738308322,13404695920] |