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 | 1 |
| 2 | 3 |
| 3 | 14 |
| 4 | 87 |
| 5 | 672 |
| 6 | 6231 |
| 7 | 67412 |
| 8 | 833475 |
| 9 | 11593140 |
| 10 | 179170947 |
| 11 | 3045978388 |
| 12 | 56490392943 |
| 13 | 1134970258372 |
| 14 | 24557211519951 |
| 15 | 569294311105300 |
| 16 | 14077429483372251 |
| 17 | 369861235318338404 |
| 18 | 10289111057247180411 |
| 19 | 302132879478864660340 |
| 20 | 9338874072977661538119 |