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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 4 |
| 3 | 12 |
| 4 | 44 |
| 5 | 116 |
| 6 | 356 |
| 7 | 948 |
| 8 | 2772 |
| 9 | 7396 |
| 10 | 20972 |
| 11 | 56108 |
| 12 | 156236 |
| 13 | 418228 |
| 14 | 1151556 |
| 15 | 3081180 |
| 16 | 8421052 |
| 17 | 22514652 |
| 18 | 61207972 |
| 19 | 163518308 |
| 20 | 442769316 |
| 21 | 1181982628 |
| 22 | 3190663628 |
| 23 | 8511628124 |
| 24 | 22920057932 |
| 25 | 61104234356 |
| 26 | 164212633412 |
[0,0,4,12,44,116,356,948,2772,7396,20972,56108, 156236,418228,1151556,3081180,8421052,22514652, 61207972,163518308,442769316,1181982628, 3190663628,8511628124,22920057932,61104234356, 164212633412] |