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 | 3 |
| 3 | 7 |
| 4 | 23 |
| 5 | 71 |
| 6 | 231 |
| 7 | 750 |
| 8 | 2479 |
| 9 | 8251 |
| 10 | 27673 |
| 11 | 93248 |
| 12 | 315515 |
| 13 | 1071097 |
| 14 | 3646618 |
| 15 | 12445982 |
| 16 | 42571327 |
| 17 | 145895599 |
| 18 | 500855361 |
| 19 | 1722062265 |
| 20 | 5929045173 |
| 21 | 20439121983 |
| 22 | 70539320558 |
| 23 | 243695962031 |
| 24 | 842704577995 |
| 25 | 2916613479471 |
| 26 | 10102511916071 |
| 27 | 35018749192885 |