The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 2 |
| 1 | 4 |
| 2 | 16 |
| 3 | 52 |
| 4 | 9232 |
| 5 | 244 |
| 6 | 9232 |
| 7 | 2464 |
| 8 | 10528 |
| 9 | 19684 |
| 10 | 88576 |
| 11 | 2270104 |
| 12 | 1008916 |
| 13 | 1594324 |
| 14 | 7174456 |
| 15 | 65451076 |
| 16 | 64570084 |
| 17 | 129140164 |
| 18 | 1570824736 |
| 19 | 1961316232 |
| 20 | 8825923024 |
| 21 | 10460353204 |
| 22 | 47071589416 |
| 23 | 105911076184 |
| 24 | 423644304724 |
| 25 | 66034034786644 |
[2,4,16,52,9232,244,9232,2464,10528,19684,88576, 2270104,1008916,1594324,7174456,65451076,64570084, 129140164,1570824736,1961316232,8825923024, 10460353204,47071589416,105911076184,423644304724, 66034034786644] |