The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 5 |
| 4 | 11 |
| 5 | 26 |
| 6 | 64 |
| 7 | 158 |
| 8 | 399 |
| 9 | 1027 |
| 10 | 2675 |
| 11 | 7052 |
| 12 | 18788 |
| 13 | 50487 |
| 14 | 136711 |
| 15 | 372687 |
| 16 | 1021942 |
| 17 | 2816873 |
| 18 | 7800510 |
| 19 | 21691134 |
| 20 | 60543553 |
| 21 | 169561453 |
| 22 | 476351239 |
| 23 | 1342002198 |
| 24 | 3790565335 |
| 25 | 10732246631 |
| 26 | 30453309502 |
| 27 | 86589559266 |
| 28 | 246672752090 |
[1,1,2,5,11,26,64,158,399,1027,2675,7052,18788, 50487,136711,372687,1021942,2816873,7800510, 21691134,60543553,169561453,476351239,1342002198, 3790565335,10732246631,30453309502,86589559266, 246672752090] |