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 | 3 |
| 3 | 17 |
| 4 | 146 |
| 5 | 1615 |
| 6 | 21895 |
| 7 | 349021 |
| 8 | 6385041 |
| 9 | 131722015 |
| 10 | 3019039806 |
| 11 | 76052414727 |
| 12 | 2087753039823 |
| 13 | 61995921313948 |
| 14 | 1979138443335708 |
| 15 | 67572818967182165 |
| 16 | 2456489615222703765 |
| 17 | 94710044795486692712 |
| 18 | 3859301582400404494533 |
| 19 | 165700769713109075755060 |