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 | 7 |
| 2 | 56 |
| 3 | 485 |
| 4 | 4032 |
| 5 | 32643 |
| 6 | 261928 |
| 7 | 2096809 |
| 8 | 16776704 |
| 9 | 134216999 |
| 10 | 1073740824 |
| 11 | 8589933261 |
| 12 | 68719475008 |
| 13 | 549755811691 |
| 14 | 4398046508360 |
| 15 | 35184372085457 |
| 16 | 281474976706560 |
| 17 | 2251799813680335 |
| 18 | 18014398509476152 |