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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 15 |
| 3 | 158 |
| 4 | 1943 |
| 5 | 26099 |
| 6 | 371128 |
| 7 | 5491868 |
| 8 | 83692617 |
| 9 | 1304579981 |
| 10 | 20703125143 |
| 11 | 333366138381 |
| 12 | 5433036837372 |
| 13 | 89448269251685 |
| 14 | 1485469625972490 |
| 15 | 24854484773368344 |
| 16 | 418581393456669989 |
| 17 | 7090045259711970090 |
| 18 | 120706208890692261466 |
| 19 | 2064356606197948427512 |
| 20 | 35449776962011108029539 |
[1,2,15,158,1943,26099,371128,5491868,83692617, 1304579981,20703125143,333366138381,5433036837372, 89448269251685,1485469625972490,24854484773368344, 418581393456669989,7090045259711970090, 120706208890692261466,2064356606197948427512, 35449776962011108029539] |