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 | 19 |
| 3 | 67 |
| 4 | 231 |
| 5 | 791 |
| 6 | 2703 |
| 7 | 9231 |
| 8 | 31519 |
| 9 | 107615 |
| 10 | 367423 |
| 11 | 1254463 |
| 12 | 4283007 |
| 13 | 14623103 |
| 14 | 49926399 |
| 15 | 170459391 |
| 16 | 581984767 |
| 17 | 1987020287 |
| 18 | 6784111615 |
| 19 | 23162405887 |
| 20 | 79081400319 |
| 21 | 270000789503 |
| 22 | 921840357375 |
| 23 | 3147359850495 |
| 24 | 10745758687231 |
| 25 | 36688315047935 |
| 26 | 125261742817279 |