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 | 13 |
| 3 | 65 |
| 4 | 355 |
| 5 | 2061 |
| 6 | 12501 |
| 7 | 78323 |
| 8 | 503033 |
| 9 | 3294373 |
| 10 | 21916883 |
| 11 | 147708777 |
| 12 | 1006330457 |
| 13 | 6919474163 |
| 14 | 47956087733 |
| 15 | 334658965641 |
| 16 | 2349535729811 |
| 17 | 16583609673797 |
| 18 | 117608812053277 |
| 19 | 837626242775875 |
| 20 | 5988634758319665 |