The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 4 |
| 2 | 14 |
| 3 | 47 |
| 4 | 157 |
| 5 | 529 |
| 6 | 1805 |
| 7 | 6238 |
| 8 | 21812 |
| 9 | 77062 |
| 10 | 274738 |
| 11 | 987276 |
| 12 | 3572568 |
| 13 | 13007398 |
| 14 | 47617798 |
| 15 | 175171543 |
| 16 | 647227453 |
| 17 | 2400843823 |
| 18 | 8937670603 |
| 19 | 33380986153 |
| 20 | 125045165773 |
| 21 | 469700405533 |
| 22 | 1768752809221 |
| 23 | 6676088636479 |
| 24 | 25252913322299 |
| 25 | 95712549267151 |
| 26 | 363441602176007 |
| 27 | 1382467779393307 |
| 28 | 5267219868722803 |
[1,4,14,47,157,529,1805,6238,21812,77062,274738, 987276,3572568,13007398,47617798,175171543, 647227453,2400843823,8937670603,33380986153, 125045165773,469700405533,1768752809221, 6676088636479,25252913322299,95712549267151, 363441602176007,1382467779393307,5267219868722803] |