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 | 6 |
| 3 | 53 |
| 4 | 554 |
| 5 | 6362 |
| 6 | 77580 |
| 7 | 986253 |
| 8 | 12927170 |
| 9 | 173452334 |
| 10 | 2370742868 |
| 11 | 32892031042 |
| 12 | 462030186916 |
| 13 | 6557906929108 |
| 14 | 93909078262808 |
| 15 | 1355087936016957 |
| 16 | 19684187540818866 |
| 17 | 287612514032460070 |
| 18 | 4224238030616082948 |
| 19 | 62329883931236020470 |
| 20 | 923519220367120779820 |