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 | 0 |
| 1 | 1 |
| 2 | 1 |
| 3 | 9 |
| 4 | 53 |
| 5 | 401 |
| 6 | 2967 |
| 7 | 23659 |
| 8 | 192615 |
| 9 | 1613687 |
| 10 | 13769538 |
| 11 | 119419761 |
| 12 | 1049154071 |
| 13 | 9318828138 |
| 14 | 83541286988 |
| 15 | 754920397795 |
| 16 | 6869170162829 |
| 17 | 62884110339333 |
| 18 | 578768613062948 |
| 19 | 5352307127138701 |
| 20 | 49708821972158231 |
| 21 | 463445557084360740 |
| 22 | 4335898935627480699 |