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 | 51 |
| 3 | 345 |
| 4 | 2602 |
| 5 | 27062 |
| 6 | 232466 |
| 7 | 1935248 |
| 8 | 17950160 |
| 9 | 155123231 |
| 10 | 1022275037 |
| 11 | 13076476440 |
| 12 | 119921146473 |
| 13 | 1100928006234 |
| 14 | 9986615648246 |
| 15 | 39453679683959 |
| 16 | 636484070277727 |
| 17 | 8477216022186037 |
| 18 | 80079195779613271 |
| 19 | 758351887226957873 |
| 20 | 7209429409009441899 |
| 21 | 68676498683402943115 |