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 | 0 |
| 2 | 1 |
| 3 | 3 |
| 4 | 13 |
| 5 | 64 |
| 6 | 369 |
| 7 | 2495 |
| 8 | 19338 |
| 9 | 169214 |
| 10 | 1649843 |
| 11 | 17735822 |
| 12 | 208395915 |
| 13 | 2657047923 |
| 14 | 36534408953 |
| 15 | 538882532060 |
| 16 | 8487399879954 |
| 17 | 142163947989232 |
| 18 | 2523410076808876 |
| 19 | 47313938940166438 |
| 20 | 934450294068287157 |