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 | 2 |
| 1 | 15 |
| 2 | 113 |
| 3 | 855 |
| 4 | 6497 |
| 5 | 49575 |
| 6 | 379793 |
| 7 | 2920695 |
| 8 | 22542017 |
| 9 | 174571335 |
| 10 | 1356217073 |
| 11 | 10567261335 |
| 12 | 82560763937 |
| 13 | 646644824295 |
| 14 | 5076269583953 |
| 15 | 39931933598775 |
| 16 | 314707907280257 |
| 17 | 2484430327672455 |
| 18 | 19642812107392433 |
| 19 | 155514083261229015 |