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 | 1 |
| 3 | 1 |
| 4 | 2 |
| 5 | 6 |
| 6 | 18 |
| 7 | 54 |
| 8 | 170 |
| 9 | 551 |
| 10 | 1817 |
| 11 | 6092 |
| 12 | 20722 |
| 13 | 71325 |
| 14 | 248055 |
| 15 | 870402 |
| 16 | 3077861 |
| 17 | 10959008 |
| 18 | 39261382 |
| 19 | 141430953 |
| 20 | 512002865 |
| 21 | 1861872379 |
| 22 | 6798330676 |
| 23 | 24915934639 |
| 24 | 91630864177 |
| 25 | 338048560865 |
| 26 | 1250793108398 |
| 27 | 4640542045919 |
| 28 | 17260221009367 |
| 29 | 64349394615738 |
| 30 | 240434325753052 |