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 | 21 |
| 3 | 364 |
| 4 | 6115 |
| 5 | 104226 |
| 6 | 1834205 |
| 7 | 33576236 |
| 8 | 641293047 |
| 9 | 12792063934 |
| 10 | 266464077769 |
| 11 | 5792423481120 |
| 12 | 131276423686979 |
| 13 | 3098383343174978 |
| 14 | 76066855087291221 |
| 15 | 1940223116685166996 |
| 16 | 51356370210296015215 |
| 17 | 1409053932006095867526 |
| 18 | 40028877611196977481857 |