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 | 1 |
| 4 | 19 |
| 5 | -128 |
| 6 | 379 |
| 7 | 1549 |
| 8 | -32600 |
| 9 | 261631 |
| 10 | -845909 |
| 11 | -10713602 |
| 12 | 237695149 |
| 13 | -2513395259 |
| 14 | 11792378662 |
| 15 | 151915180429 |
| 16 | -4826456213273 |
| 17 | 70741388773960 |
| 18 | -558513179369297 |
| 19 | -2833805536521839 |
| 20 | 200720356696607416 |
| 21 | -4256279445015662093 |
| 22 | 54120395442382043743 |
| 23 | -173423789950999240226 |