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 | 2 |
| 4 | 11 |
| 5 | 24 |
| 6 | 93 |
| 7 | 272 |
| 8 | 971 |
| 9 | 3194 |
| 10 | 11293 |
| 11 | 39148 |
| 12 | 139687 |
| 13 | 497756 |
| 14 | 1798002 |
| 15 | 6517194 |
| 16 | 23807731 |
| 17 | 87336870 |
| 18 | 322082967 |
| 19 | 1192381270 |
| 20 | 4431889344 |
| 21 | 16527495396 |
| 22 | 61831374003 |
| 23 | 231973133544 |
| 24 | 872598922407 |
| 25 | 3290312724374 |
| 26 | 12434632908623 |
| 27 | 47089829065940 |
| 28 | 178672856753641 |