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 | -2 |
| 2 | -2 |
| 3 | -2 |
| 4 | -6 |
| 5 | -10 |
| 6 | -34 |
| 7 | -82 |
| 8 | -254 |
| 9 | -730 |
| 10 | -2238 |
| 11 | -6826 |
| 12 | -21370 |
| 13 | -67122 |
| 14 | -213654 |
| 15 | -684258 |
| 16 | -2208694 |
| 17 | -7169298 |
| 18 | -23402738 |
| 19 | -76748130 |
| 20 | -252790518 |
| 21 | -835816658 |
| 22 | -2773236614 |
| 23 | -9230776706 |
| 24 | -30814377058 |
| 25 | -103139338858 |
| 26 | -346067984622 |
| 27 | -1163810570178 |