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 | 1 |
| 2 | 11 |
| 3 | 21 |
| 4 | 131 |
| 5 | 341 |
| 6 | 1651 |
| 7 | 5061 |
| 8 | 21571 |
| 9 | 72181 |
| 10 | 287891 |
| 11 | 1009701 |
| 12 | 3888611 |
| 13 | 13985621 |
| 14 | 52871731 |
| 15 | 192727941 |
| 16 | 721445251 |
| 17 | 2648724661 |
| 18 | 9863177171 |
| 19 | 36350423781 |
| 20 | 134982195491 |
| 21 | 498486433301 |
| 22 | 1848308388211 |
| 23 | 6833172721221 |
| 24 | 25316256603331 |
| 25 | 93647983815541 |
| 26 | 346810549848851 |