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 | 21 |
| 2 | 105 |
| 3 | 266 |
| 4 | 1386 |
| 5 | 6678 |
| 6 | 25403 |
| 7 | 100506 |
| 8 | 384678 |
| 9 | 1393903 |
| 10 | 4831890 |
| 11 | 15955485 |
| 12 | 50080478 |
| 13 | 149211930 |
| 14 | 421819950 |
| 15 | 1132236630 |
| 16 | 2890927935 |
| 17 | 7040892159 |
| 18 | 16411041500 |
| 19 | 36733789575 |
| 20 | 79230165105 |
| 21 | 165194651065 |
| 22 | 333926559540 |