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 | 7 |
| 2 | 28 |
| 3 | 158 |
| 4 | 1087 |
| 5 | 8420 |
| 6 | 69034 |
| 7 | 586400 |
| 8 | 5097725 |
| 9 | 45088364 |
| 10 | 404211372 |
| 11 | 3663020374 |
| 12 | 33489909119 |
| 13 | 308457775318 |
| 14 | 2858876653517 |
| 15 | 26639629964435 |
| 16 | 249393774431034 |
| 17 | 2344318827962046 |
| 18 | 22116397163892861 |
| 19 | 209317713089716899 |
| 20 | 1986761935587919881 |
| 21 | 18906449884370307192 |