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 | 3 |
| 3 | 12 |
| 4 | 63 |
| 5 | 418 |
| 6 | 3460 |
| 7 | 35309 |
| 8 | 434879 |
| 9 | 6296319 |
| 10 | 104601742 |
| 11 | 1956519181 |
| 12 | 40622160668 |
| 13 | 926192254412 |
| 14 | 22993939511337 |
| 15 | 617288387438399 |
| 16 | 17815464892300869 |
| 17 | 550018928405927892 |
| 18 | 18086444341575141093 |
| 19 | 631071177229005331170 |
| 20 | 23286118567945953909224 |