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 | -2 |
| 3 | -5 |
| 4 | -29 |
| 5 | -232 |
| 6 | -2231 |
| 7 | -24745 |
| 8 | -308917 |
| 9 | -4279945 |
| 10 | -65179552 |
| 11 | -1082598411 |
| 12 | -19480497765 |
| 13 | -377583928402 |
| 14 | -7844313743160 |
| 15 | -173920273954426 |
| 16 | -4099686000487330 |
| 17 | -102398103973448577 |
| 18 | -2701860620027906307 |
| 19 | -75107104456422563041 |
| 20 | -2194183661233574578401 |