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 | 4 |
| 2 | 16 |
| 3 | 60 |
| 4 | 228 |
| 5 | 860 |
| 6 | 3267 |
| 7 | 12426 |
| 8 | 47471 |
| 9 | 181812 |
| 10 | 698512 |
| 11 | 2690086 |
| 12 | 10384712 |
| 13 | 40170182 |
| 14 | 155681112 |
| 15 | 604362074 |
| 16 | 2349783665 |
| 17 | 9148780570 |
| 18 | 35665860725 |
| 19 | 139202880860 |
| 20 | 543887439194 |
| 21 | 2127148912456 |
| 22 | 8326877989146 |
| 23 | 32623644335536 |