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 | 2 |
| 3 | 85 |
| 4 | 926 |
| 5 | 5461 |
| 6 | 37130 |
| 7 | 349525 |
| 8 | 2973350 |
| 9 | 22369621 |
| 10 | 174174002 |
| 11 | 1431655765 |
| 12 | 11582386286 |
| 13 | 91625968981 |
| 14 | 729520967450 |
| 15 | 5864062014805 |
| 16 | 47006639297270 |
| 17 | 375299968947541 |
| 18 | 2999857885752002 |
| 19 | 24019198012642645 |
| 20 | 192222214478506046 |
| 21 | 1537228672809129301 |