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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 9 |
| 3 | 19 |
| 4 | 53 |
| 5 | 111 |
| 6 | 309 |
| 7 | 647 |
| 8 | 1801 |
| 9 | 3771 |
| 10 | 10497 |
| 11 | 21979 |
| 12 | 61181 |
| 13 | 128103 |
| 14 | 356589 |
| 15 | 746639 |
| 16 | 2078353 |
| 17 | 4351731 |
| 18 | 12113529 |
| 19 | 25363747 |
| 20 | 70602821 |
| 21 | 147830751 |
| 22 | 411503397 |
| 23 | 861620759 |
| 24 | 2398417561 |
| 25 | 5021893803 |
| 26 | 13979001969 |
| 27 | 29269742059 |
| 28 | 81475594253 |
[1,3,9,19,53,111,309,647,1801,3771,10497,21979, 61181,128103,356589,746639,2078353,4351731, 12113529,25363747,70602821,147830751,411503397, 861620759,2398417561,5021893803,13979001969, 29269742059,81475594253] |