The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 2 |
| 3 | 3 |
| 4 | 4 |
| 5 | 4 |
| 6 | 7 |
| 7 | 20 |
| 8 | 21 |
| 9 | 45 |
| 10 | 145 |
| 11 | 212 |
| 12 | 436 |
| 13 | 2161 |
| 14 | 2791 |
| 15 | 8995 |
| 16 | 40480 |
| 17 | 86264 |
| 18 | 264562 |
| 19 | 1826697 |
| 20 | 3632340 |
| 21 | 16824438 |
| 22 | 112933447 |
| 23 | 337629371 |
| 24 | 1472886340 |
| 25 | 15531543956 |
| 26 | 43332027600 |
| 27 | 293975081405 |
| 28 | 2889767925722 |
| 29 | 12600532736321 |
| 30 | 79696537663155 |
[1,2,2,3,4,4,7,20,21,45,145,212,436,2161,2791, 8995,40480,86264,264562,1826697,3632340,16824438, 112933447,337629371,1472886340,15531543956, 43332027600,293975081405,2889767925722, 12600532736321,79696537663155] |