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 | 2 |
| 2 | 3 |
| 3 | 10 |
| 4 | 69 |
| 5 | 678 |
| 6 | 8496 |
| 7 | 128316 |
| 8 | 2258262 |
| 9 | 45292494 |
| 10 | 1018882779 |
| 11 | 25399668480 |
| 12 | 694999352141 |
| 13 | 20710476430548 |
| 14 | 667708554093132 |
| 15 | 23159551588872624 |
| 16 | 860001996926543616 |
| 17 | 34043670528120810846 |
| 18 | 1431191816223150995395 |