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 | 20 |
| 2 | 400 |
| 3 | 4884 |
| 4 | 41682 |
| 5 | 273959 |
| 6 | 1477240 |
| 7 | 6818350 |
| 8 | 27746619 |
| 9 | 101698292 |
| 10 | 341120712 |
| 11 | 1060013078 |
| 12 | 3081189588 |
| 13 | 8443340635 |
| 14 | 21952389700 |
| 15 | 54443494785 |
| 16 | 129382581759 |
| 17 | 295772387822 |
| 18 | 652604111790 |
| 19 | 1393875593290 |
| 20 | 2889329636208 |
| 21 | 5825806879833 |