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| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 18 |
| 3 | 150 |
| 4 | 1275 |
| 5 | 11033 |
| 6 | 96768 |
| 7 | 857440 |
| 8 | 7658001 |
| 9 | 68827440 |
| 10 | 621769016 |
| 11 | 5640718746 |
| 12 | 51355222113 |
| 13 | 468976190634 |
| 14 | 4293892636600 |
| 15 | 39403880112240 |
| 16 | 362321464909965 |
| 17 | 3337465898598408 |
| 18 | 30791007409655928 |
| 19 | 284475382593582680 |
| 20 | 2631594710532743340 |
| 21 | 24372218297220901965 |
| 22 | 225958143637966827240 |
[2,18,150,1275,11033,96768,857440,7658001, 68827440,621769016,5640718746,51355222113, 468976190634,4293892636600,39403880112240, 362321464909965,3337465898598408, 30791007409655928,284475382593582680, 2631594710532743340,24372218297220901965, 225958143637966827240] |