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 | 3 |
| 2 | 18 |
| 3 | 117 |
| 4 | 801 |
| 5 | 5724 |
| 6 | 42633 |
| 7 | 331911 |
| 8 | 2717874 |
| 9 | 23620329 |
| 10 | 220260789 |
| 11 | 2228505372 |
| 12 | 24681015981 |
| 13 | 300506801715 |
| 14 | 4017984855786 |
| 15 | 58675338993069 |
| 16 | 928673101727001 |
| 17 | 15804592586240220 |
| 18 | 287174716511520033 |
| 19 | 5538727108037507535 |