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 | 1 |
| 2 | 9 |
| 3 | 25 |
| 4 | 241 |
| 5 | 1041 |
| 6 | 10681 |
| 7 | 60649 |
| 8 | 658785 |
| 9 | 4540321 |
| 10 | 51972841 |
| 11 | 415198521 |
| 12 | 4988808529 |
| 13 | 44847866545 |
| 14 | 563683953561 |
| 15 | 5586645006601 |
| 16 | 73228719433921 |
| 17 | 788319280278849 |
| 18 | 10747425123292105 |
| 19 | 124265401483446361 |
| 20 | 1757874020223846321 |
| 21 | 21640338257575264081 |