The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 1 |
| 3 | 0 |
| 4 | 3 |
| 5 | 4 |
| 6 | 20 |
| 7 | 62 |
| 8 | 251 |
| 9 | 1002 |
| 10 | 4295 |
| 11 | 19086 |
| 12 | 88369 |
| 13 | 423957 |
| 14 | 2104214 |
| 15 | 10783054 |
| 16 | 56969183 |
| 17 | 309900293 |
| 18 | 1733790827 |
| 19 | 9965992962 |
| 20 | 58801256594 |
| 21 | 355808106682 |
| 22 | 2206237014216 |
| 23 | 14007443494601 |
| 24 | 90994768741426 |
| 25 | 604395083728629 |
| 26 | 4101881493676885 |
| 27 | 28426771732773415 |
| 28 | 201044377117957190 |
| 29 | 1450195412613951590 |
| 30 | 10663346917944740350 |
| 31 | 79885242459500736025 |
[1,0,1,0,3,4,20,62,251,1002,4295,19086,88369, 423957,2104214,10783054,56969183,309900293, 1733790827,9965992962,58801256594,355808106682, 2206237014216,14007443494601,90994768741426, 604395083728629,4101881493676885, 28426771732773415,201044377117957190, 1450195412613951590,10663346917944740350, 79885242459500736025] |