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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 22 |
| 3 | 138 |
| 4 | 889 |
| 5 | 4921 |
| 6 | 26687 |
| 7 | 154539 |
| 8 | 870270 |
| 9 | 4437621 |
| 10 | 20367762 |
| 11 | 86589471 |
| 12 | 388661761 |
| 13 | 2366418106 |
| 14 | 18602433227 |
| 15 | 142978182070 |
| 16 | 952075901928 |
| 17 | 5434361620523 |
| 18 | 27064481351856 |
| 19 | 120477919973804 |
| 20 | 497320625548529 |
| 21 | 2051776298637086 |
| 22 | 9590295679377844 |
| 23 | 54933121828772931 |
[1,22,138,889,4921,26687,154539,870270,4437621, 20367762,86589471,388661761,2366418106, 18602433227,142978182070,952075901928, 5434361620523,27064481351856,120477919973804, 497320625548529,2051776298637086,9590295679377844, 54933121828772931] |