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 | 3 |
| 3 | 13 |
| 4 | 71 |
| 5 | 487 |
| 6 | 3965 |
| 7 | 37306 |
| 8 | 398048 |
| 9 | 4748201 |
| 10 | 62627000 |
| 11 | 905067008 |
| 12 | 14223441093 |
| 13 | 241516427253 |
| 14 | 4406723053134 |
| 15 | 85987611417777 |
| 16 | 1786851267779817 |
| 17 | 39397336701986187 |
| 18 | 918633226468153628 |
| 19 | 22585761594590716490 |
| 20 | 583972625166308889970 |