This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 5 |
| 4 | 15 |
| 5 | 51 |
| 6 | 189 |
| 7 | 746 |
| 8 | 3091 |
| 9 | 13311 |
| 10 | 59146 |
| 11 | 269701 |
| 12 | 1256820 |
| 13 | 5966001 |
| 14 | 28773252 |
| 15 | 140695923 |
| 16 | 696332678 |
| 17 | 3483193924 |
| 18 | 17589239130 |
| 19 | 89575160517 |
| 20 | 459648885327 |
| 21 | 2374883298183 |
| 22 | 12346911196912 |
| 23 | 64555427595970 |
| 24 | 339276669116222 |
| 25 | 1791578092326881 |
| 26 | 9501960180835998 |