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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 4 |
| 2 | 13 |
| 3 | 43 |
| 4 | 141 |
| 5 | 467 |
| 6 | 1588 |
| 7 | 5544 |
| 8 | 19966 |
| 9 | 74344 |
| 10 | 286395 |
| 11 | 1141611 |
| 12 | 4707358 |
| 13 | 20063872 |
| 14 | 88312177 |
| 15 | 400980431 |
| 16 | 1875954361 |
| 17 | 9032585846 |
| 18 | 44709095467 |
| 19 | 227245218669 |
| 20 | 1184822316447 |
| 21 | 6330552351751 |
| 22 | 34630331194626 |
| 23 | 193785391735685 |
| 24 | 1108363501628097 |
| 25 | 6474568765976164 |
[1,4,13,43,141,467,1588,5544,19966,74344,286395, 1141611,4707358,20063872,88312177,400980431, 1875954361,9032585846,44709095467,227245218669, 1184822316447,6330552351751,34630331194626, 193785391735685,1108363501628097,6474568765976164] |