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 | 4 |
| 3 | 23 |
| 4 | 154 |
| 5 | 1124 |
| 6 | 8675 |
| 7 | 69626 |
| 8 | 575243 |
| 9 | 4859778 |
| 10 | 41789764 |
| 11 | 364565277 |
| 12 | 3218581695 |
| 13 | 28702642553 |
| 14 | 258172627259 |
| 15 | 2339496034381 |
| 16 | 21337716782873 |
| 17 | 195726876816623 |
| 18 | 1804472496834650 |
| 19 | 16711389876481027 |
| 20 | 155395461519245354 |
| 21 | 1450298253483719944 |