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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 4 |
| 3 | 0 |
| 4 | 28 |
| 5 | 56 |
| 6 | 116 |
| 7 | 224 |
| 8 | 476 |
| 9 | 984 |
| 10 | 1940 |
| 11 | 3840 |
| 12 | 7420 |
| 13 | 14584 |
| 14 | 30196 |
| 15 | 60384 |
| 16 | 116700 |
| 17 | 241624 |
| 18 | 479124 |
| 19 | 954112 |
| 20 | 1920252 |
| 21 | 3836152 |
| 22 | 7685620 |
| 23 | 15412192 |
| 24 | 30689244 |
| 25 | 60993496 |
| 26 | 123015060 |
| 27 | 244240128 |
| 28 | 491359484 |
| 29 | 974276856 |
| 30 | 1973421556 |
| 31 | 3948932064 |
| 32 | 7889455068 |
[1,0,4,0,28,56,116,224,476,984,1940,3840,7420, 14584,30196,60384,116700,241624,479124,954112, 1920252,3836152,7685620,15412192,30689244, 60993496,123015060,244240128,491359484,974276856, 1973421556,3948932064,7889455068] |