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 | 3 |
| 2 | 21 |
| 3 | 168 |
| 4 | 1425 |
| 5 | 12483 |
| 6 | 111594 |
| 7 | 1011636 |
| 8 | 9264753 |
| 9 | 85510590 |
| 10 | 794087151 |
| 11 | 7410887718 |
| 12 | 69446624910 |
| 13 | 653019755430 |
| 14 | 6158495001960 |
| 15 | 58226492157048 |
| 16 | 551725482707505 |
| 17 | 5238008159399163 |
| 18 | 49814314319342424 |
| 19 | 474467729545936650 |
| 20 | 4525387365179378775 |