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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 10 |
| 3 | 56 |
| 4 | 363 |
| 5 | 2540 |
| 6 | 18719 |
| 7 | 143084 |
| 8 | 1123888 |
| 9 | 9015938 |
| 10 | 73553356 |
| 11 | 608356076 |
| 12 | 5089508859 |
| 13 | 42992095102 |
| 14 | 366179399391 |
| 15 | 3141310120084 |
| 16 | 27117461481521 |
| 17 | 235389702516728 |
| 18 | 2053329861556631 |
| 19 | 17990275294687148 |
| 20 | 158246298370021478 |
| 21 | 1396954300222929984 |
[1,2,10,56,363,2540,18719,143084,1123888,9015938, 73553356,608356076,5089508859,42992095102, 366179399391,3141310120084,27117461481521, 235389702516728,2053329861556631, 17990275294687148,158246298370021478, 1396954300222929984] |