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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 6 |
| 3 | 22 |
| 4 | 89 |
| 5 | 370 |
| 6 | 1585 |
| 7 | 6986 |
| 8 | 31317 |
| 9 | 142230 |
| 10 | 654000 |
| 11 | 3035518 |
| 12 | 14185121 |
| 13 | 66714076 |
| 14 | 315565582 |
| 15 | 1499290539 |
| 16 | 7150770043 |
| 17 | 34228613264 |
| 18 | 164347352327 |
| 19 | 791165781965 |
| 20 | 3817852791465 |
| 21 | 18463872731698 |
| 22 | 89464611676312 |
| 23 | 434234627305046 |
| 24 | 2111009783379968 |
| 25 | 10277298441170561 |
| 26 | 50098781177467074 |
| 27 | 244508877664193913 |
[1,2,6,22,89,370,1585,6986,31317,142230,654000, 3035518,14185121,66714076,315565582,1499290539, 7150770043,34228613264,164347352327,791165781965, 3817852791465,18463872731698,89464611676312, 434234627305046,2111009783379968, 10277298441170561,50098781177467074, 244508877664193913] |