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 | 1 |
| 2 | 5 |
| 3 | 19 |
| 4 | 69 |
| 5 | 235 |
| 6 | 789 |
| 7 | 2603 |
| 8 | 8533 |
| 9 | 27819 |
| 10 | 90453 |
| 11 | 293547 |
| 12 | 951637 |
| 13 | 3082923 |
| 14 | 9983317 |
| 15 | 32320171 |
| 16 | 104617301 |
| 17 | 338602667 |
| 18 | 1095849301 |
| 19 | 3546458795 |
| 20 | 11477013845 |
| 21 | 37141260971 |
| 22 | 120193373525 |
| 23 | 388957383339 |
| 24 | 1258699445589 |
| 25 | 4073250794155 |
| 26 | 13181344109909 |
| 27 | 42655780874923 |