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 | 9 |
| 4 | 100 |
| 5 | 1065 |
| 6 | 10626 |
| 7 | 224161 |
| 8 | 4598504 |
| 9 | 46288017 |
| 10 | 2509940710 |
| 11 | 84061763841 |
| 12 | -1602021820596 |
| 13 | 164372205860473 |
| 14 | 5216105126641514 |
| 15 | -883395389739028095 |
| 16 | 79008645559978113616 |
| 17 | -1023235751229436800735 |
| 18 | -651030746777115881959602 |
| 19 | 113943411938145511923004513 |