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 | 4 |
| 1 | 13 |
| 2 | 43 |
| 3 | 151 |
| 4 | 559 |
| 5 | 2143 |
| 6 | 8383 |
| 7 | 33151 |
| 8 | 131839 |
| 9 | 525823 |
| 10 | 2100223 |
| 11 | 8394751 |
| 12 | 33566719 |
| 13 | 134242303 |
| 14 | 536920063 |
| 15 | 2147581951 |
| 16 | 8590131199 |
| 17 | 34360131583 |
| 18 | 137439739903 |
| 19 | 549757386751 |
| 20 | 2199026401279 |
| 21 | 8796099313663 |
| 22 | 35184384671743 |
| 23 | 140737513521151 |
| 24 | 562950003752959 |
| 25 | 2251799914348543 |