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 | 3 |
| 2 | 12 |
| 3 | 87 |
| 4 | 684 |
| 5 | 5463 |
| 6 | 43692 |
| 7 | 349527 |
| 8 | 2796204 |
| 9 | 22369623 |
| 10 | 178956972 |
| 11 | 1431655767 |
| 12 | 11453246124 |
| 13 | 91625968983 |
| 14 | 733007751852 |
| 15 | 5864062014807 |
| 16 | 46912496118444 |
| 17 | 375299968947543 |
| 18 | 3002399751580332 |
| 19 | 24019198012642647 |
| 20 | 192153584101141164 |