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 | 1 |
| 2 | 4 |
| 3 | 20 |
| 4 | 129 |
| 5 | 1012 |
| 6 | 9341 |
| 7 | 99213 |
| 8 | 1191392 |
| 9 | 15958404 |
| 10 | 235939211 |
| 11 | 3817327362 |
| 12 | 67103292438 |
| 13 | 1273789853650 |
| 14 | 25973844914959 |
| 15 | 566329335460917 |
| 16 | 13150556885604115 |
| 17 | 324045146807055210 |
| 18 | 8446201774570017379 |
| 19 | 232198473069120178475 |
| 20 | 6715304449424099384968 |