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| n | a(n) |
|---|---|
| 1 | 4 |
| 2 | 34 |
| 3 | 320 |
| 4 | 2958 |
| 5 | 27692 |
| 6 | 250934 |
| 7 | 2338508 |
| 8 | 21159320 |
| 9 | 192619880 |
| 10 | 1767181410 |
| 11 | 16165706444 |
| 12 | 147550684090 |
| 13 | 1348528674604 |
| 14 | 12330783808396 |
| 15 | 112700663242560 |
| 16 | 1029964489404282 |
| 17 | 9413986758909060 |
| 18 | 86046903897714270 |
| 19 | 786467010156728596 |
[4,34,320,2958,27692,250934,2338508,21159320, 192619880,1767181410,16165706444,147550684090, 1348528674604,12330783808396,112700663242560, 1029964489404282,9413986758909060, 86046903897714270,786467010156728596] |