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 | 2 |
| 3 | 3 |
| 4 | 10 |
| 5 | 25 |
| 6 | 71 |
| 7 | 203 |
| 8 | 562 |
| 9 | 1650 |
| 10 | 4667 |
| 11 | 13673 |
| 12 | 39427 |
| 13 | 115440 |
| 14 | 336639 |
| 15 | 987628 |
| 16 | 2898658 |
| 17 | 8529257 |
| 18 | 25134200 |
| 19 | 74173606 |
| 20 | 219207815 |
| 21 | 648546314 |
| 22 | 1921045953 |
| 23 | 5695642513 |
| 24 | 16902924883 |
| 25 | 50203798050 |
| 26 | 149229323544 |
| 27 | 443895849894 |
| 28 | 1321292939459 |
| 29 | 3935377071154 |
| 30 | 11728037768186 |