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) |
|---|---|
| 1 | 5 |
| 2 | 21 |
| 3 | 142 |
| 4 | 1059 |
| 5 | 8360 |
| 6 | 68940 |
| 7 | 586140 |
| 8 | 5096885 |
| 9 | 45085903 |
| 10 | 404203228 |
| 11 | 3663001812 |
| 12 | 33489858047 |
| 13 | 308457620524 |
| 14 | 2858876200536 |
| 15 | 26639628764285 |
| 16 | 249393770865090 |
| 17 | 2344318815695001 |
| 18 | 22116397127183516 |
| 19 | 209317713015989446 |
| 20 | 1986761935255798075 |
| 21 | 18906449883376272709 |