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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 11 |
| 4 | 50 |
| 5 | 278 |
| 6 | 1860 |
| 7 | 14793 |
| 8 | 138166 |
| 9 | 1494034 |
| 10 | 18422609 |
| 11 | 255359957 |
| 12 | 3929301362 |
| 13 | 66412322717 |
| 14 | 1222216175058 |
| 15 | 24314268876147 |
| 16 | 519701698551031 |
| 17 | 11874016816562299 |
| 18 | 288722141589331161 |
| 19 | 7442890569982739838 |
| 20 | 202733505298293899570 |
| 21 | 5817564888930184685708 |
[1,1,3,11,50,278,1860,14793,138166,1494034, 18422609,255359957,3929301362,66412322717, 1222216175058,24314268876147,519701698551031, 11874016816562299,288722141589331161, 7442890569982739838,202733505298293899570, 5817564888930184685708] |