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 | -1 |
| 3 | -6 |
| 4 | -23 |
| 5 | -94 |
| 6 | -380 |
| 7 | -1539 |
| 8 | -6231 |
| 9 | -25229 |
| 10 | -102150 |
| 11 | -413597 |
| 12 | -1674620 |
| 13 | -6780398 |
| 14 | -27453271 |
| 15 | -111156025 |
| 16 | -450061557 |
| 17 | -1822262042 |
| 18 | -7378188379 |
| 19 | -29873674862 |
| 20 | -120956040144 |
| 21 | -489741008259 |
| 22 | -1982920860215 |
| 23 | -8028682653825 |
| 24 | -32507472410594 |
| 25 | -131620068707297 |
| 26 | -532918778418092 |
| 27 | -2157744082494058 |
| 28 | -8736527429861839 |
| 29 | -35373477397979841 |
| 30 | -143224285995880937 |