The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 0 |
| 3 | 0 |
| 4 | 1 |
| 5 | 1 |
| 6 | 2 |
| 7 | 5 |
| 8 | 6 |
| 9 | 15 |
| 10 | 24 |
| 11 | 45 |
| 12 | 85 |
| 13 | 155 |
| 14 | 288 |
| 15 | 550 |
| 16 | 1008 |
| 17 | 1935 |
| 18 | 3626 |
| 19 | 6885 |
| 20 | 13107 |
| 21 | 24940 |
| 22 | 47616 |
| 23 | 91225 |
| 24 | 174590 |
| 25 | 335626 |
| 26 | 645120 |
| 27 | 1242600 |
| 28 | 2396745 |
| 29 | 4627915 |
| 30 | 8947294 |
| 31 | 17318945 |
| 32 | 33552384 |
| 33 | 65076240 |
| 34 | 126320640 |
| 35 | 245424829 |
| 36 | 477218560 |
| 37 | 928638035 |
| 38 | 1808400384 |
| 39 | 3524082400 |
| 40 | 6871921458 |
| 41 | 13408691175 |
| 42 | 26178823218 |
[1,0,0,1,1,2,5,6,15,24,45,85,155,288,550,1008, 1935,3626,6885,13107,24940,47616,91225,174590, 335626,645120,1242600,2396745,4627915,8947294, 17318945,33552384,65076240,126320640,245424829, 477218560,928638035,1808400384,3524082400, 6871921458,13408691175,26178823218] |