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 | 0 |
| 2 | 3 |
| 3 | 18 |
| 4 | 73 |
| 5 | 256 |
| 6 | 844 |
| 7 | 2709 |
| 8 | 8596 |
| 9 | 27146 |
| 10 | 85560 |
| 11 | 269464 |
| 12 | 848400 |
| 13 | 2670859 |
| 14 | 8407805 |
| 15 | 26467163 |
| 16 | 83316232 |
| 17 | 262271397 |
| 18 | 825604226 |
| 19 | 2598919135 |
| 20 | 8181135469 |
| 21 | 25753388928 |
| 22 | 81069068693 |
| 23 | 255197243733 |
| 24 | 803335158081 |
| 25 | 2528817970143 |