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 | -9 |
| 3 | -54 |
| 4 | 426 |
| 5 | 6426 |
| 6 | -50274 |
| 7 | -1465884 |
| 8 | 10992996 |
| 9 | 552727476 |
| 10 | -3792193524 |
| 11 | -312571718424 |
| 12 | 1853425616616 |
| 13 | 248005863100296 |
| 14 | -1173524207653224 |
| 15 | -263102748395914224 |
| 16 | 865735128320476176 |
| 17 | 359884863190774985616 |
| 18 | -584551982838131141904 |
| 19 | -616984573598760535235424 |
| 20 | -155177934223071790979424 |