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 | 3 |
| 2 | 27 |
| 3 | 340 |
| 4 | 5070 |
| 5 | 83559 |
| 6 | 1472261 |
| 7 | 27205308 |
| 8 | 520974180 |
| 9 | 10257025240 |
| 10 | 206469879462 |
| 11 | 4232227325352 |
| 12 | 88073315164471 |
| 13 | 1856404180514940 |
| 14 | 39560345751767970 |
| 15 | 851083806077023888 |
| 16 | 18462636758298743712 |
| 17 | 403459312929849694791 |
| 18 | 8874351725505564788350 |