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 | 4 |
| 2 | 17 |
| 3 | 98 |
| 4 | 561 |
| 5 | 3000 |
| 6 | 15409 |
| 7 | 77782 |
| 8 | 390113 |
| 9 | 1952396 |
| 10 | 9764625 |
| 11 | 48826794 |
| 12 | 244138897 |
| 13 | 1220700928 |
| 14 | 6103512881 |
| 15 | 30517574750 |
| 16 | 152587886529 |
| 17 | 762939448212 |
| 18 | 3814697259793 |
| 19 | 19073486321266 |
| 20 | 95367431632625 |