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 | -1 |
| 3 | -4 |
| 4 | -11 |
| 5 | -30 |
| 6 | -79 |
| 7 | -208 |
| 8 | -545 |
| 9 | -1428 |
| 10 | -3739 |
| 11 | -9790 |
| 12 | -25631 |
| 13 | -67104 |
| 14 | -175681 |
| 15 | -459940 |
| 16 | -1204139 |
| 17 | -3152478 |
| 18 | -8253295 |
| 19 | -21607408 |
| 20 | -56568929 |
| 21 | -148099380 |
| 22 | -387729211 |
| 23 | -1015088254 |
| 24 | -2657535551 |
| 25 | -6957518400 |
| 26 | -18215019649 |
| 27 | -47687540548 |
| 28 | -124847601995 |
| 29 | -326855265438 |