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 | 5 |
| 2 | 26 |
| 3 | 137 |
| 4 | 722 |
| 5 | 3785 |
| 6 | 19706 |
| 7 | 101897 |
| 8 | 523682 |
| 9 | 2677385 |
| 10 | 13629386 |
| 11 | 69136457 |
| 12 | 349699442 |
| 13 | 1764742985 |
| 14 | 8889229466 |
| 15 | 44709799817 |
| 16 | 224608392002 |
| 17 | 1127293880585 |
| 18 | 5653520131946 |
| 19 | 28335932715977 |
| 20 | 141953379225362 |
| 21 | 710862920970185 |