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 | 3 |
| 2 | -18 |
| 3 | -135 |
| 4 | -405 |
| 5 | -1944 |
| 6 | -8019 |
| 7 | -24057 |
| 8 | -91854 |
| 9 | -334611 |
| 10 | -1003833 |
| 11 | -3542940 |
| 12 | -12223143 |
| 13 | -36669429 |
| 14 | -124357194 |
| 15 | -416118303 |
| 16 | -1248354909 |
| 17 | -4132485216 |
| 18 | -13559717115 |
| 19 | -40679151345 |
| 20 | -132497807238 |
| 21 | -428874481323 |
| 22 | -1286623443969 |
| 23 | -4142299868388 |