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 | 9 |
| 4 | 28 |
| 5 | 205 |
| 6 | 726 |
| 7 | 8659 |
| 8 | 47384 |
| 9 | 562545 |
| 10 | 4234330 |
| 11 | 68588311 |
| 12 | 483088332 |
| 13 | 10699776685 |
| 14 | 102434734598 |
| 15 | 2016289908585 |
| 16 | 24588487650736 |
| 17 | 611171244308689 |
| 18 | 6456997293606738 |
| 19 | 209020565553571999 |
| 20 | 2838875160624256460 |