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 | 129 |
| 5 | 1269 |
| 6 | 15147 |
| 7 | 213765 |
| 8 | 3475329 |
| 9 | 64020585 |
| 10 | 1317472563 |
| 11 | 29960707545 |
| 12 | 746086414785 |
| 13 | 20192521440285 |
| 14 | 590166330458715 |
| 15 | 18525204423695565 |
| 16 | 621571306435103745 |
| 17 | 22199954036873457105 |
| 18 | 840913892465144800995 |
| 19 | 33672216851574639900705 |