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) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 1 |
| 5 | 5 |
| 6 | 17 |
| 7 | 56 |
| 8 | 182 |
| 9 | 573 |
| 10 | 1792 |
| 11 | 5533 |
| 12 | 16977 |
| 13 | 51652 |
| 14 | 156291 |
| 15 | 470069 |
| 16 | 1407264 |
| 17 | 4193977 |
| 18 | 12451760 |
| 19 | 36838994 |
| 20 | 108656009 |
| 21 | 319583578 |
| 22 | 937634011 |
| 23 | 2744720126 |
| 24 | 8018165821 |
| 25 | 23379886511 |
| 26 | 68056985580 |
| 27 | 197800670948 |
| 28 | 574068309840 |
| 29 | 1663907364480 |
| 30 | 4816910618093 |
| 31 | 13929036720057 |