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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 9 |
| 3 | 46 |
| 4 | 184 |
| 5 | 640 |
| 6 | 2032 |
| 7 | 6048 |
| 8 | 17152 |
| 9 | 46848 |
| 10 | 124160 |
| 11 | 321024 |
| 12 | 813056 |
| 13 | 2023424 |
| 14 | 4960256 |
| 15 | 12001280 |
| 16 | 28704768 |
| 17 | 67960832 |
| 18 | 159449088 |
| 19 | 371064832 |
| 20 | 857210880 |
| 21 | 1967128576 |
| 22 | 4486856704 |
| 23 | 10177478656 |
| 24 | 22968008704 |
| 25 | 51589939200 |
| 26 | 115376914432 |
[0,1,9,46,184,640,2032,6048,17152,46848,124160, 321024,813056,2023424,4960256,12001280,28704768, 67960832,159449088,371064832,857210880,1967128576, 4486856704,10177478656,22968008704,51589939200, 115376914432] |