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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 2 |
| 2 | 12 |
| 3 | 58 |
| 4 | 307 |
| 5 | 1550 |
| 6 | 7781 |
| 7 | 39003 |
| 8 | 195195 |
| 9 | 976315 |
| 10 | 4882299 |
| 11 | 24413043 |
| 12 | 122068292 |
| 13 | 610347461 |
| 14 | 3051749613 |
| 15 | 15258772698 |
| 16 | 76293912556 |
| 17 | 381469661013 |
| 18 | 1907348501745 |
| 19 | 9536742901936 |
| 20 | 47683715296045 |
| 21 | 238418578052990 |
| 22 | 1192092893410662 |
| 23 | 5960464473344773 |
[0,2,12,58,307,1550,7781,39003,195195,976315, 4882299,24413043,122068292,610347461,3051749613, 15258772698,76293912556,381469661013, 1907348501745,9536742901936,47683715296045, 238418578052990,1192092893410662,5960464473344773] |