The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 5 |
| 3 | 17 |
| 4 | 76 |
| 5 | 422 |
| 6 | 2809 |
| 7 | 21821 |
| 8 | 193708 |
| 9 | 1934468 |
| 10 | 21465529 |
| 11 | 262007033 |
| 12 | 3488768650 |
| 13 | 50326173458 |
| 14 | 781808322481 |
| 15 | 13012772925293 |
| 16 | 231029881905736 |
| 17 | 4358082011900744 |
| 18 | 87045479653871377 |
| 19 | 1835177785479753545 |
| 20 | 40727378713879346206 |
| 21 | 949039029924830652662 |
[1,2,5,17,76,422,2809,21821,193708,1934468, 21465529,262007033,3488768650,50326173458, 781808322481,13012772925293,231029881905736, 4358082011900744,87045479653871377, 1835177785479753545,40727378713879346206, 949039029924830652662] |