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 | 19 |
| 4 | 129 |
| 5 | 1071 |
| 6 | 10743 |
| 7 | 125455 |
| 8 | 1675439 |
| 9 | 25167073 |
| 10 | 420070323 |
| 11 | 7712503173 |
| 12 | 154475622513 |
| 13 | 3351859639363 |
| 14 | 78324320723561 |
| 15 | 1960968388497523 |
| 16 | 52368881358012435 |
| 17 | 1485952518531483045 |
| 18 | 44643697199669589447 |
| 19 | 1415782273405809697009 |