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 | 4 |
| 3 | 12 |
| 4 | 40 |
| 5 | 128 |
| 6 | 416 |
| 7 | 1344 |
| 8 | 4224 |
| 9 | 12928 |
| 10 | 38016 |
| 11 | 104832 |
| 12 | 260096 |
| 13 | 512256 |
| 14 | 329728 |
| 15 | -4140032 |
| 16 | -33444864 |
| 17 | -184423424 |
| 18 | -883798016 |
| 19 | -3935711232 |
| 20 | -16759001088 |
| 21 | -69266997248 |
| 22 | -280327684096 |
| 23 | -1116872122368 |
| 24 | -4394989174784 |
| 25 | -17112512544768 |
| 26 | -65974620848128 |