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 | 0 |
| 2 | 0 |
| 3 | 13 |
| 4 | 170 |
| 5 | 1605 |
| 6 | 13390 |
| 7 | 104993 |
| 8 | 794010 |
| 9 | 5867245 |
| 10 | 42681830 |
| 11 | 307120473 |
| 12 | 2192847250 |
| 13 | 15570312485 |
| 14 | 110116458270 |
| 15 | 776528783953 |
| 16 | 5464646634890 |
| 17 | 38398786511325 |
| 18 | 269529019274710 |
| 19 | 1890415785439433 |
| 20 | 13251574765596930 |