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 | -2 |
| 3 | -2 |
| 4 | -5 |
| 5 | -9 |
| 6 | -36 |
| 7 | -104 |
| 8 | -365 |
| 9 | -1219 |
| 10 | -4213 |
| 11 | -14617 |
| 12 | -51570 |
| 13 | -183084 |
| 14 | -656536 |
| 15 | -2370066 |
| 16 | -8613590 |
| 17 | -31478538 |
| 18 | -115632718 |
| 19 | -426676244 |
| 20 | -1580878746 |
| 21 | -5878933054 |
| 22 | -21936060630 |
| 23 | -82100980070 |
| 24 | -308146839623 |
| 25 | -1159545407027 |
| 26 | -4373730398473 |
| 27 | -16533813947503 |