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| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 52 |
| 3 | 219 |
| 4 | 956 |
| 5 | 4304 |
| 6 | 19843 |
| 7 | 90153 |
| 8 | 411915 |
| 9 | 1883419 |
| 10 | 8606261 |
| 11 | 39318528 |
| 12 | 179689129 |
| 13 | 821125409 |
| 14 | 3752220577 |
| 15 | 17146552549 |
| 16 | 78354832275 |
| 17 | 358057427672 |
| 18 | 1636215092867 |
| 19 | 7477016924526 |
| 20 | 34167732374529 |
| 21 | 156136328399884 |
| 22 | 713496452583759 |
[2,52,219,956,4304,19843,90153,411915,1883419, 8606261,39318528,179689129,821125409,3752220577, 17146552549,78354832275,358057427672, 1636215092867,7477016924526,34167732374529, 156136328399884,713496452583759] |