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 | 0 |
| 1 | 3 |
| 2 | 21 |
| 3 | 102 |
| 4 | 426 |
| 5 | 1641 |
| 6 | 6015 |
| 7 | 21324 |
| 8 | 73812 |
| 9 | 250959 |
| 10 | 841449 |
| 11 | 2790066 |
| 12 | 9167358 |
| 13 | 29893557 |
| 14 | 96855123 |
| 15 | 312088728 |
| 16 | 1000836264 |
| 17 | 3196219035 |
| 18 | 10169787837 |
| 19 | 32252755710 |
| 20 | 101988443730 |
| 21 | 321655860993 |
| 22 | 1012039172391 |
| 23 | 3177332285412 |
| 24 | 9955641160956 |
| 25 | 31137856397031 |