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 | 15 |
| 3 | 96 |
| 4 | 431 |
| 5 | 2104 |
| 6 | 10734 |
| 7 | 53995 |
| 8 | 270584 |
| 9 | 1360373 |
| 10 | 6842490 |
| 11 | 34397698 |
| 12 | 172916932 |
| 13 | 869345996 |
| 14 | 4370695957 |
| 15 | 21973721785 |
| 16 | 110473467193 |
| 17 | 555410077197 |
| 18 | 2792348324294 |
| 19 | 14038652292860 |
| 20 | 70579951706145 |
| 21 | 354843911694537 |