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 | 23 |
| 3 | 150 |
| 4 | 1037 |
| 5 | 7408 |
| 6 | 54035 |
| 7 | 399850 |
| 8 | 2990105 |
| 9 | 22540260 |
| 10 | 170991647 |
| 11 | 1303789534 |
| 12 | 9983164453 |
| 13 | 76711854040 |
| 14 | 591236890667 |
| 15 | 4568611684306 |
| 16 | 35382196437041 |
| 17 | 274564234870732 |
| 18 | 2134337640202295 |
| 19 | 16617270658727878 |