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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 4 |
| 3 | 4 |
| 4 | 16 |
| 5 | 68 |
| 6 | 212 |
| 7 | 776 |
| 8 | 3076 |
| 9 | 11540 |
| 10 | 44944 |
| 11 | 177748 |
| 12 | 700292 |
| 13 | 2779272 |
| 14 | 11069140 |
| 15 | 44107780 |
| 16 | 176038288 |
| 17 | 703199588 |
| 18 | 2809956020 |
| 19 | 11232774920 |
| 20 | 44913243940 |
| 21 | 179603461748 |
| 22 | 718287355024 |
| 23 | 2872823053300 |
| 24 | 11490415637348 |
| 25 | 45959392743048 |
[0,4,4,16,68,212,776,3076,11540,44944,177748, 700292,2779272,11069140,44107780,176038288, 703199588,2809956020,11232774920,44913243940, 179603461748,718287355024,2872823053300, 11490415637348,45959392743048] |