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| n | a(n) |
|---|---|
| 4 | 1 |
| 5 | 4 |
| 6 | 9 |
| 7 | 23 |
| 8 | 57 |
| 9 | 139 |
| 10 | 336 |
| 11 | 811 |
| 12 | 1960 |
| 13 | 4732 |
| 14 | 11424 |
| 15 | 27580 |
| 16 | 66585 |
| 17 | 160752 |
| 18 | 388089 |
| 19 | 936931 |
| 20 | 2261953 |
| 21 | 5460839 |
| 22 | 13183632 |
| 23 | 31828103 |
| 24 | 76839840 |
| 25 | 185507784 |
| 26 | 447855408 |
| 27 | 1081218600 |
| 28 | 2610292609 |
| 29 | 6301803820 |
| 30 | 15213900249 |
| 31 | 36729604319 |
| 32 | 88673108889 |
| 33 | 214075822099 |
| 34 | 516824753088 |
[1,4,9,23,57,139,336,811,1960,4732,11424,27580, 66585,160752,388089,936931,2261953,5460839, 13183632,31828103,76839840,185507784,447855408, 1081218600,2610292609,6301803820,15213900249, 36729604319,88673108889,214075822099,516824753088] |