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 | 7 |
| 3 | 28 |
| 4 | 105 |
| 5 | 357 |
| 6 | 1197 |
| 7 | 3857 |
| 8 | 12300 |
| 9 | 38430 |
| 10 | 118874 |
| 11 | 362670 |
| 12 | 1095430 |
| 13 | 3271751 |
| 14 | 9673993 |
| 15 | 28310881 |
| 16 | 82033609 |
| 17 | 235359901 |
| 18 | 668779076 |
| 19 | 1882412994 |
| 20 | 5249817573 |
| 21 | 14510628853 |