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 | 1 |
| 2 | 2 |
| 3 | 7 |
| 4 | 28 |
| 5 | 127 |
| 6 | 650 |
| 7 | 3737 |
| 8 | 23996 |
| 9 | 170866 |
| 10 | 1338578 |
| 11 | 11446714 |
| 12 | 106063630 |
| 13 | 1057817614 |
| 14 | 11288886056 |
| 15 | 128243813228 |
| 16 | 1543828592478 |
| 17 | 19616461337281 |
| 18 | 262178561430244 |
| 19 | 3674568043513202 |
| 20 | 53861542554953612 |
| 21 | 823710227331537712 |