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 | 0 |
| 2 | 1 |
| 3 | 2 |
| 4 | 7 |
| 5 | 20 |
| 6 | 71 |
| 7 | 240 |
| 8 | 871 |
| 9 | 3148 |
| 10 | 11655 |
| 11 | 43332 |
| 12 | 162769 |
| 13 | 614198 |
| 14 | 2330537 |
| 15 | 8875768 |
| 16 | 33924859 |
| 17 | 130038230 |
| 18 | 499753855 |
| 19 | 1924912894 |
| 20 | 7429160296 |
| 21 | 28723877732 |
| 22 | 111236423288 |
| 23 | 431403470222 |
| 24 | 1675316535350 |
| 25 | 6513837679610 |
| 26 | 25354842100894 |
| 27 | 98794053269694 |
| 28 | 385312558571890 |
| 29 | 1504105116253904 |
| 30 | 5876236938019298 |
| 31 | 22974847399695092 |