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| n | a(n) |
|---|---|
| 2 | 1 |
| 3 | 10 |
| 4 | 91 |
| 5 | 651 |
| 6 | 4026 |
| 7 | 22737 |
| 8 | 120835 |
| 9 | 615043 |
| 10 | 3031678 |
| 11 | 14578928 |
| 12 | 68747966 |
| 13 | 319075550 |
| 14 | 1461581460 |
| 15 | 6621579135 |
| 16 | 29718121635 |
| 17 | 132302508195 |
| 18 | 584868588150 |
| 19 | 2569600678260 |
| 20 | 11227927978410 |
| 21 | 48822435838410 |
| 22 | 211370463290220 |
| 23 | 911509393468050 |
| 24 | 3916793943349326 |
| 25 | 16776146058210126 |
| 26 | 71641860657928876 |
[1,10,91,651,4026,22737,120835,615043,3031678, 14578928,68747966,319075550,1461581460,6621579135, 29718121635,132302508195,584868588150, 2569600678260,11227927978410,48822435838410, 211370463290220,911509393468050,3916793943349326, 16776146058210126,71641860657928876] |