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 | 4 |
| 3 | 15 |
| 4 | 57 |
| 5 | 221 |
| 6 | 872 |
| 7 | 3489 |
| 8 | 14113 |
| 9 | 57575 |
| 10 | 236457 |
| 11 | 976271 |
| 12 | 4047871 |
| 13 | 16840879 |
| 14 | 70259892 |
| 15 | 293790127 |
| 16 | 1230783085 |
| 17 | 5164196117 |
| 18 | 21696512073 |
| 19 | 91254256589 |
| 20 | 384165925259 |
| 21 | 1618551762085 |
| 22 | 6823801074549 |
| 23 | 28785680471185 |
| 24 | 121490461772347 |