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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 6 |
| 3 | 13 |
| 4 | 22 |
| 5 | 60 |
| 6 | 147 |
| 7 | 310 |
| 8 | 723 |
| 9 | 1723 |
| 10 | 3917 |
| 11 | 8973 |
| 12 | 20875 |
| 13 | 48427 |
| 14 | 111384 |
| 15 | 256857 |
| 16 | 599340 |
| 17 | 1384994 |
| 18 | 3187563 |
| 19 | 7469888 |
| 20 | 17334233 |
| 21 | 39905291 |
| 22 | 94076289 |
| 23 | 219435873 |
| 24 | 505824167 |
| 25 | 1202595689 |
| 26 | 2825927772 |
| 27 | 6530389759 |
| 28 | 15704159500 |
| 29 | 37297212976 |
[1,6,13,22,60,147,310,723,1723,3917,8973,20875, 48427,111384,256857,599340,1384994,3187563, 7469888,17334233,39905291,94076289,219435873, 505824167,1202595689,2825927772,6530389759, 15704159500,37297212976] |