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 | 4 |
| 4 | 10 |
| 5 | 26 |
| 6 | 76 |
| 7 | 232 |
| 8 | 764 |
| 9 | 2620 |
| 10 | 9496 |
| 11 | 35696 |
| 12 | 140152 |
| 13 | 568503 |
| 14 | 2390466 |
| 15 | 10349340 |
| 16 | 46204720 |
| 17 | 211779200 |
| 18 | 997134592 |
| 19 | 4808141824 |
| 20 | 23745792032 |
| 21 | 119848119307 |
| 22 | 618058083314 |
| 23 | 3251373425356 |
| 24 | 17442275104496 |
| 25 | 95297400355320 |
| 26 | 530067682582320 |
| 27 | 2998503402985440 |