The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 4 |
| 3 | 10 |
| 4 | 31 |
| 5 | 82 |
| 6 | 256 |
| 7 | 730 |
| 8 | 2218 |
| 9 | 6571 |
| 10 | 19768 |
| 11 | 59050 |
| 12 | 177430 |
| 13 | 531442 |
| 14 | 1595056 |
| 15 | 4783060 |
| 16 | 14351125 |
| 17 | 43046722 |
| 18 | 129146980 |
| 19 | 387420490 |
| 20 | 1162281262 |
| 21 | 3486785140 |
| 22 | 10460412256 |
| 23 | 31381059610 |
| 24 | 94143358444 |
| 25 | 282429536563 |
| 26 | 847289140888 |
| 27 | 2541865834900 |
| 28 | 7625599080070 |
| 29 | 22876792454962 |
[1,4,10,31,82,256,730,2218,6571,19768,59050, 177430,531442,1595056,4783060,14351125,43046722, 129146980,387420490,1162281262,3486785140, 10460412256,31381059610,94143358444,282429536563, 847289140888,2541865834900,7625599080070, 22876792454962] |