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 | 9 |
| 2 | 35 |
| 3 | 153 |
| 4 | 707 |
| 5 | 3369 |
| 6 | 16355 |
| 7 | 80313 |
| 8 | 397187 |
| 9 | 1972809 |
| 10 | 9824675 |
| 11 | 49005273 |
| 12 | 244672067 |
| 13 | 1222297449 |
| 14 | 6108298595 |
| 15 | 30531927033 |
| 16 | 152630937347 |
| 17 | 763068593289 |
| 18 | 3815084686115 |
| 19 | 19074648589593 |
| 20 | 95370918425027 |
| 21 | 476847618556329 |