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 | 31 |
| 2 | 149 |
| 3 | 559 |
| 4 | 2457 |
| 5 | 10861 |
| 6 | 49253 |
| 7 | 226033 |
| 8 | 1048177 |
| 9 | 4898197 |
| 10 | 23033019 |
| 11 | 108861553 |
| 12 | 516705009 |
| 13 | 2461341589 |
| 14 | 11760895827 |
| 15 | 56346974689 |
| 16 | 270594033729 |
| 17 | 1302160086037 |
| 18 | 6277836418979 |
| 19 | 30315976817857 |
| 20 | 146614887333487 |