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 | 1 |
| 3 | -7 |
| 4 | -23 |
| 5 | -1 |
| 6 | 7 |
| 7 | -103 |
| 8 | -251 |
| 9 | -133 |
| 10 | -149 |
| 11 | -1387 |
| 12 | -3143 |
| 13 | -3001 |
| 14 | -4913 |
| 15 | -19663 |
| 16 | -42611 |
| 17 | -55693 |
| 18 | -101549 |
| 19 | -291667 |
| 20 | -612863 |
| 21 | -960001 |
| 22 | -1831433 |
| 23 | -4460023 |
| 24 | -9185771 |
| 25 | -15980053 |
| 26 | -31162949 |
| 27 | -69500347 |
| 28 | -141392183 |
| 29 | -261261001 |