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 | 9 |
| 3 | 45 |
| 4 | 201 |
| 5 | 819 |
| 6 | 3357 |
| 7 | 13329 |
| 8 | 52215 |
| 9 | 199686 |
| 10 | 750733 |
| 11 | 2774793 |
| 12 | 10112184 |
| 13 | 36357280 |
| 14 | 129131448 |
| 15 | 453379226 |
| 16 | 1574884565 |
| 17 | 5415956550 |
| 18 | 18450934294 |
| 19 | 62303210591 |
| 20 | 208624947952 |
| 21 | 693066815809 |
| 22 | 2285129922950 |
| 23 | 7480504628754 |
| 24 | 24320897894515 |
| 25 | 78557786077315 |