| n | a(n) |
|---|---|
| 0 | 2 |
| 1 | 4 |
| 2 | 8 |
| 3 | 24 |
| 4 | 60 |
| 5 | 152 |
| 6 | 400 |
| 7 | 1032 |
| 8 | 2656 |
| 9 | 6876 |
| 10 | 17776 |
| 11 | 45912 |
| 12 | 118664 |
| 13 | 306680 |
| 14 | 792480 |
| 15 | 2047984 |
| 16 | 5292564 |
| 17 | 13677160 |
| 18 | 35345112 |
| 19 | 91340568 |
| 20 | 236046088 |
| 21 | 610000528 |
| 22 | 1576390448 |
| 23 | 4073776744 |
| 24 | 10527631456 |
| 25 | 27205966108 |
| 26 | 70306845872 |
| 27 | 181690021616 |
| 28 | 469531293752 |
| 29 | 1213383282936 |
[2,4,8,24,60,152,400,1032,2656,6876,17776,45912, 118664,306680,792480,2047984,5292564,13677160, 35345112,91340568,236046088,610000528,1576390448, 4073776744,10527631456,27205966108,70306845872, 181690021616,469531293752,1213383282936] |