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 | 7 |
| 3 | 55 |
| 4 | 529 |
| 5 | 6121 |
| 6 | 82711 |
| 7 | 1273567 |
| 8 | 21945505 |
| 9 | 417540529 |
| 10 | 8680953511 |
| 11 | 195582295591 |
| 12 | 4742407056817 |
| 13 | 123045795823705 |
| 14 | 3399348471640759 |
| 15 | 99573135106176271 |
| 16 | 3081061456572152641 |
| 17 | 100382623544966098657 |
| 18 | 3433727597233037475655 |
| 19 | 123000248740384210119319 |
| 20 | 4603377404407810366309201 |