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 | 49 |
| 4 | 361 |
| 5 | 2601 |
| 6 | 19881 |
| 7 | 154449 |
| 8 | 1225449 |
| 9 | 9853321 |
| 10 | 80156209 |
| 11 | 658076409 |
| 12 | 5444816521 |
| 13 | 45343869481 |
| 14 | 379735715529 |
| 15 | 3195538786449 |
| 16 | 27004932177129 |
| 17 | 229066136374761 |
| 18 | 1949470542590481 |
| 19 | 16640188083903609 |
| 20 | 142415188146838161 |
| 21 | 1221800234100831441 |
| 22 | 10504959504381567729 |