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 | 0 |
| 3 | 3 |
| 4 | -8 |
| 5 | 9 |
| 6 | 19 |
| 7 | -141 |
| 8 | 448 |
| 9 | -759 |
| 10 | -951 |
| 11 | 14355 |
| 12 | -71810 |
| 13 | 238617 |
| 14 | -421622 |
| 15 | -1283181 |
| 16 | 17699702 |
| 17 | -110524503 |
| 18 | 494858579 |
| 19 | -1480719213 |
| 20 | 12947578 |
| 21 | 41684591673 |
| 22 | -396443074054 |
| 23 | 2562153015315 |
| 24 | -12548536326806 |
| 25 | 39305562343881 |
| 26 | 52542301031459 |
| 27 | -2158744047173613 |