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| n | a(n) |
|---|---|
| 1 | 42 |
| 2 | 212 |
| 3 | 992 |
| 4 | 3876 |
| 5 | 15448 |
| 6 | 64644 |
| 7 | 252056 |
| 8 | 989988 |
| 9 | 4108676 |
| 10 | 16147220 |
| 11 | 63393540 |
| 12 | 266083460 |
| 13 | 1047285272 |
| 14 | 4245874244 |
| 15 | 16903342544 |
| 16 | 67034166420 |
| 17 | 274274527940 |
| 18 | 1068738181764 |
| 19 | 4246566244100 |
| 20 | 17369295361736 |
| 21 | 67322784388376 |
| 22 | 269731897678032 |
[42,212,992,3876,15448,64644,252056,989988, 4108676,16147220,63393540,266083460,1047285272, 4245874244,16903342544,67034166420,274274527940, 1068738181764,4246566244100,17369295361736, 67322784388376,269731897678032] |