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 | 4 |
| 1 | 13 |
| 2 | 45 |
| 3 | 153 |
| 4 | 523 |
| 5 | 1785 |
| 6 | 6095 |
| 7 | 20809 |
| 8 | 71047 |
| 9 | 242569 |
| 10 | 828183 |
| 11 | 2827593 |
| 12 | 9654007 |
| 13 | 32960841 |
| 14 | 112535351 |
| 15 | 384219721 |
| 16 | 1311808183 |
| 17 | 4478793289 |
| 18 | 15291556791 |
| 19 | 52208640585 |
| 20 | 178251448759 |
| 21 | 608588513865 |
| 22 | 2077851157943 |
| 23 | 7094227604041 |
| 24 | 24221208100279 |
| 25 | 82696377193033 |