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 | 12 |
| 2 | 102 |
| 3 | 688 |
| 4 | 4029 |
| 5 | 21156 |
| 6 | 102246 |
| 7 | 461448 |
| 8 | 1967658 |
| 9 | 7990996 |
| 10 | 31110432 |
| 11 | 116685288 |
| 12 | 423366831 |
| 13 | 1490904528 |
| 14 | 5110173678 |
| 15 | 17088259888 |
| 16 | 55862240688 |
| 17 | 178836472032 |
| 18 | 561532752086 |
| 19 | 1731639278904 |
| 20 | 5250722230962 |