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 | 3 |
| 3 | 5 |
| 4 | 20 |
| 5 | 56 |
| 6 | 225 |
| 7 | 819 |
| 8 | 3333 |
| 9 | 13336 |
| 10 | 55231 |
| 11 | 229146 |
| 12 | 963284 |
| 13 | 4068503 |
| 14 | 17301000 |
| 15 | 73893082 |
| 16 | 317013121 |
| 17 | 1364917667 |
| 18 | 5896350458 |
| 19 | 25545737979 |
| 20 | 110968732581 |