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 | 12 |
| 4 | 76 |
| 5 | 961 |
| 6 | 15407 |
| 7 | 221528 |
| 8 | 3260936 |
| 9 | 80774113 |
| 10 | 2462081967 |
| 11 | 50963779604 |
| 12 | 922244742292 |
| 13 | 61063845514113 |
| 14 | 2868669700179871 |
| 15 | 2019727494212912 |
| 16 | -47889136910252848 |
| 17 | 461395118866593115713 |
| 18 | 5781219348638565771423 |
| 19 | -2108738296748190078596084 |