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 | 3 |
| 1 | 15 |
| 2 | 83 |
| 3 | 495 |
| 4 | 3107 |
| 5 | 20175 |
| 6 | 134003 |
| 7 | 903855 |
| 8 | 6161987 |
| 9 | 42326415 |
| 10 | 292299923 |
| 11 | 2026332015 |
| 12 | 14085959267 |
| 13 | 98111307855 |
| 14 | 684331371443 |
| 15 | 4778093436975 |
| 16 | 33385561506947 |
| 17 | 233393582580495 |
| 18 | 1632228682596563 |
| 19 | 11417969833962735 |