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) |
|---|---|
| 1 | 0 |
| 2 | 4 |
| 3 | 84 |
| 4 | 1074 |
| 5 | 11058 |
| 6 | 102448 |
| 7 | 896026 |
| 8 | 7578952 |
| 9 | 62820362 |
| 10 | 514178822 |
| 11 | 4174954460 |
| 12 | 33725176208 |
| 13 | 271523097884 |
| 14 | 2181288088576 |
| 15 | 17498432045552 |
| 16 | 140241880816930 |
| 17 | 1123280018219562 |
| 18 | 8993350007112124 |
| 19 | 71984384316723134 |
| 20 | 576073752326317448 |
| 21 | 4609640266662591130 |