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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 3 |
| 3 | 26 |
| 4 | 320 |
| 5 | 4776 |
| 6 | 81018 |
| 7 | 1510336 |
| 8 | 30328173 |
| 9 | 647535770 |
| 10 | 14569480376 |
| 11 | 343234151688 |
| 12 | 8425926474186 |
| 13 | 214747018423616 |
| 14 | 5665854689772960 |
| 15 | 154393844206506248 |
| 16 | 4337151982457354192 |
| 17 | 125404753959532852236 |
| 18 | 3727264826995512243092 |
| 19 | 113749283318621304173840 |
| 20 | 3560977119168952929308604 |
[1,3,26,320,4776,81018,1510336,30328173,647535770, 14569480376,343234151688,8425926474186, 214747018423616,5665854689772960, 154393844206506248,4337151982457354192, 125404753959532852236,3727264826995512243092, 113749283318621304173840, 3560977119168952929308604] |