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 | 0 |
| 2 | 1 |
| 3 | 4 |
| 4 | 34 |
| 5 | 387 |
| 6 | 5596 |
| 7 | 97149 |
| 8 | 1959938 |
| 9 | 44956945 |
| 10 | 1154208544 |
| 11 | 32772977715 |
| 12 | 1019467710328 |
| 13 | 34473686833527 |
| 14 | 1259038828370402 |
| 15 | 49388615245426933 |
| 16 | 2070991708598960524 |
| 17 | 92445181295983865757 |
| 18 | 4376733266230674345874 |
| 19 | 219058079619119072854095 |
| 20 | 11556990682657196214302036 |