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 | 5 |
| 3 | 16 |
| 4 | 86 |
| 5 | 448 |
| 6 | 3580 |
| 7 | 34981 |
| 8 | 448628 |
| 9 | 6854130 |
| 10 | 121173330 |
| 11 | 2403140605 |
| 12 | 52655943500 |
| 13 | 1260724587515 |
| 14 | 32726520985365 |
| 15 | 915263580719998 |
| 16 | 27432853858637678 |
| 17 | 877211481667946811 |
| 18 | 29807483816421710806 |
| 19 | 1072542780403547030073 |
| 20 | 40739888428757581326987 |