The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 6 |
| 3 | 34 |
| 4 | 210 |
| 5 | 1378 |
| 6 | 9726 |
| 7 | 73314 |
| 8 | 588846 |
| 9 | 5018290 |
| 10 | 45216798 |
| 11 | 429290178 |
| 12 | 4281260386 |
| 13 | 44724792130 |
| 14 | 488185773782 |
| 15 | 5555082575762 |
| 16 | 65760600166734 |
| 17 | 808339570702354 |
| 18 | 10299822335353654 |
| 19 | 135828836289073570 |
| 20 | 1851208197237464530 |
| 21 | 26040184250745321058 |
[0,1,6,34,210,1378,9726,73314,588846,5018290, 45216798,429290178,4281260386,44724792130, 488185773782,5555082575762,65760600166734, 808339570702354,10299822335353654, 135828836289073570,1851208197237464530, 26040184250745321058] |