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 | 4 |
| 3 | -11 |
| 4 | 29 |
| 5 | -76 |
| 6 | 199 |
| 7 | -521 |
| 8 | 1364 |
| 9 | -3571 |
| 10 | 9349 |
| 11 | -24476 |
| 12 | 64079 |
| 13 | -167761 |
| 14 | 439204 |
| 15 | -1149851 |
| 16 | 3010349 |
| 17 | -7881196 |
| 18 | 20633239 |
| 19 | -54018521 |
| 20 | 141422324 |
| 21 | -370248451 |
| 22 | 969323029 |
| 23 | -2537720636 |
| 24 | 6643838879 |
| 25 | -17393796001 |
| 26 | 45537549124 |
| 27 | -119218851371 |