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 | 57 |
| 3 | 495 |
| 4 | 4401 |
| 5 | 39447 |
| 6 | 354537 |
| 7 | 3189375 |
| 8 | 28700001 |
| 9 | 258286887 |
| 10 | 2324542617 |
| 11 | 20920765455 |
| 12 | 188286534801 |
| 13 | 1694577750327 |
| 14 | 15251196564297 |
| 15 | 137260759512735 |
| 16 | 1235346806916801 |
| 17 | 11118121176157767 |
| 18 | 100063090327139577 |
| 19 | 900567812169415215 |