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 | 3 |
| 2 | 5 |
| 3 | -9 |
| 4 | -111 |
| 5 | -477 |
| 6 | -1051 |
| 7 | 1095 |
| 8 | 21793 |
| 9 | 106947 |
| 10 | 276165 |
| 11 | -71145 |
| 12 | -4712655 |
| 13 | -26071965 |
| 14 | -76452315 |
| 15 | -29748249 |
| 16 | 1045547073 |
| 17 | 6564746115 |
| 18 | 21507513221 |
| 19 | 19922192439 |
| 20 | -230801512751 |
| 21 | -1674387214173 |
| 22 | -6072718662555 |