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 | 1 |
| 2 | 1 |
| 3 | -26 |
| 4 | -107 |
| 5 | 136 |
| 6 | 9181 |
| 7 | 53488 |
| 8 | -427895 |
| 9 | -10486016 |
| 10 | -43859879 |
| 11 | 1373548672 |
| 12 | 23512856797 |
| 13 | -30564574208 |
| 14 | -6412871847563 |
| 15 | -73709639926784 |
| 16 | 1060067525174929 |
| 17 | 40587133606543360 |
| 18 | 179320588932698929 |
| 19 | -14474677657838059520 |
| 20 | -306563699887974043739 |
| 21 | 2301792469199499132928 |