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 | -3 |
| 3 | 13 |
| 4 | -51 |
| 5 | 205 |
| 6 | -819 |
| 7 | 3277 |
| 8 | -13107 |
| 9 | 52429 |
| 10 | -209715 |
| 11 | 838861 |
| 12 | -3355443 |
| 13 | 13421773 |
| 14 | -53687091 |
| 15 | 214748365 |
| 16 | -858993459 |
| 17 | 3435973837 |
| 18 | -13743895347 |
| 19 | 54975581389 |
| 20 | -219902325555 |
| 21 | 879609302221 |
| 22 | -3518437208883 |
| 23 | 14073748835533 |