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) |
|---|---|
| 1 | 1 |
| 2 | 4 |
| 3 | 15 |
| 4 | 56 |
| 5 | 213 |
| 6 | 813 |
| 7 | 3104 |
| 8 | 9632089 |
| 9 | 36787239 |
| 10 | 140499215 |
| 11 | 2049402728 |
| 12 | 7827156489 |
| 13 | 29893772401 |
| 14 | 6360445726168 |
| 15 | 24292055125871 |
| 16 | 354337952833519 |
| 17 | 5168578128432327 |
| 18 | 19740029272114749 |
| 19 | 4200051540382303047 |
| 20 | 16040995858310522148 |
| 21 | 233983234616956426935 |
| 22 | 893637628328498285466 |
| 23 | 3413014663516027432461 |