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) |
|---|---|
| 1 | 3 |
| 2 | 7 |
| 3 | 31 |
| 4 | 211 |
| 5 | 2311 |
| 6 | 43891 |
| 7 | 1272811 |
| 8 | 47093971 |
| 9 | 2213416591 |
| 10 | 148298911531 |
| 11 | 15274787887591 |
| 12 | 2734187031878611 |
| 13 | 522229723088814511 |
| 14 | 116457228248805635731 |
| 15 | 31559908855426327282831 |
| 16 | 9247053294639913893869191 |
| 17 | 2931315894400852704356533231 |
| 18 | 1691369271069292010413719673711 |