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) |
|---|---|
| 1 | 1 |
| 2 | -2 |
| 3 | 5 |
| 4 | -13 |
| 5 | 30 |
| 6 | -74 |
| 7 | 202 |
| 8 | -616 |
| 9 | 2126 |
| 10 | -7828 |
| 11 | 29366 |
| 12 | -110398 |
| 13 | 414214 |
| 14 | -1556848 |
| 15 | 5892713 |
| 16 | -22524354 |
| 17 | 86954484 |
| 18 | -338421674 |
| 19 | 1324660464 |
| 20 | -5204326208 |
| 21 | 20498580511 |
| 22 | -80907096678 |
| 23 | 320002290542 |
| 24 | -1268500509496 |
| 25 | 5040195484362 |
| 26 | -20073242195580 |
| 27 | 80120884387322 |
| 28 | -320442284717582 |
| 29 | 1283939790460139 |