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 | 0 |
| 2 | -3 |
| 3 | -3 |
| 4 | -6 |
| 5 | -12 |
| 6 | -27 |
| 7 | -63 |
| 8 | -153 |
| 9 | -381 |
| 10 | -969 |
| 11 | -2505 |
| 12 | -6564 |
| 13 | -17394 |
| 14 | -46533 |
| 15 | -125505 |
| 16 | -340902 |
| 17 | -931716 |
| 18 | -2560401 |
| 19 | -7070337 |
| 20 | -19609146 |
| 21 | -54597852 |
| 22 | -152556057 |
| 23 | -427642677 |
| 24 | -1202289669 |
| 25 | -3389281245 |
| 26 | -9578183391 |
| 27 | -27130207503 |
| 28 | -77009455428 |
| 29 | -219023318406 |