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 | 19 |
| 3 | 271 |
| 4 | 4579 |
| 5 | 78151 |
| 6 | 1363573 |
| 7 | 24072133 |
| 8 | 429042211 |
| 9 | 7702189345 |
| 10 | 139071924069 |
| 11 | 2522948398895 |
| 12 | 45949039890469 |
| 13 | 839611990929219 |
| 14 | 15385356833972711 |
| 15 | 282616668487409521 |
| 16 | 5202536118941844771 |
| 17 | 95950964483217949751 |
| 18 | 1772592132899627652691 |
| 19 | 32795665902734099555845 |