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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 12 |
| 3 | 86 |
| 4 | 666 |
| 5 | 5388 |
| 6 | 44832 |
| 7 | 380424 |
| 8 | 3275172 |
| 9 | 28512248 |
| 10 | 250413856 |
| 11 | 2215112886 |
| 12 | 19711078686 |
| 13 | 176276723508 |
| 14 | 1583186541144 |
| 15 | 14271487891512 |
| 16 | 129063176166570 |
| 17 | 1170480053359908 |
| 18 | 10641805703955624 |
| 19 | 96970507481607972 |
| 20 | 885397365149468076 |
| 21 | 8098908925136867112 |
[1,2,12,86,666,5388,44832,380424,3275172,28512248, 250413856,2215112886,19711078686,176276723508, 1583186541144,14271487891512,129063176166570, 1170480053359908,10641805703955624, 96970507481607972,885397365149468076, 8098908925136867112] |