| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 4 |
| 3 | 12 |
| 4 | 42 |
| 5 | 164 |
| 6 | 688 |
| 7 | 3024 |
| 8 | 13680 |
| 9 | 63110 |
| 10 | 295520 |
| 11 | 1401012 |
| 12 | 6713280 |
| 13 | 32470468 |
| 14 | 158343504 |
| 15 | 777725264 |
| 16 | 3843992546 |
| 17 | 19104857608 |
| 18 | 95419519076 |
| 19 | 478668009828 |
| 20 | 2410698765472 |
| 21 | 12184259877320 |
| 22 | 61782045169312 |
| 23 | 314202878599696 |
| 24 | 1602270787137472 |
| 25 | 8191160756085318 |
| 26 | 41971595130249968 |
| 27 | 215522156779513584 |
[1,2,4,12,42,164,688,3024,13680,63110,295520, 1401012,6713280,32470468,158343504,777725264, 3843992546,19104857608,95419519076,478668009828, 2410698765472,12184259877320,61782045169312, 314202878599696,1602270787137472,8191160756085318, 41971595130249968,215522156779513584] |