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 | 7 |
| 3 | 17 |
| 4 | 49 |
| 5 | 139 |
| 6 | 393 |
| 7 | 1113 |
| 8 | 3151 |
| 9 | 8921 |
| 10 | 25257 |
| 11 | 71507 |
| 12 | 202449 |
| 13 | 573169 |
| 14 | 1622743 |
| 15 | 4594273 |
| 16 | 13007201 |
| 17 | 36825691 |
| 18 | 104260057 |
| 19 | 295178697 |
| 20 | 835703199 |
| 21 | 2366023849 |
| 22 | 6698632793 |
| 23 | 18965016483 |
| 24 | 53693322401 |
| 25 | 152015310561 |
| 26 | 430382282407 |
| 27 | 1218488508337 |
| 28 | 3449756892049 |