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 | 61 |
| 4 | 295 |
| 5 | 1447 |
| 6 | 7151 |
| 7 | 35491 |
| 8 | 176597 |
| 9 | 880125 |
| 10 | 4390901 |
| 11 | 21920913 |
| 12 | 109486993 |
| 13 | 547018941 |
| 14 | 2733608905 |
| 15 | 13662695645 |
| 16 | 68294088535 |
| 17 | 341399727335 |
| 18 | 1706739347095 |
| 19 | 8532741458075 |
| 20 | 42660172763995 |
| 21 | 213287735579135 |
| 22 | 1066389745361635 |
| 23 | 5331765761680895 |