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 | 3 |
| 2 | 9 |
| 3 | 25 |
| 4 | 71 |
| 5 | 201 |
| 6 | 569 |
| 7 | 1611 |
| 8 | 4561 |
| 9 | 12913 |
| 10 | 36559 |
| 11 | 103505 |
| 12 | 293041 |
| 13 | 829651 |
| 14 | 2348889 |
| 15 | 6650121 |
| 16 | 18827671 |
| 17 | 53304473 |
| 18 | 150914409 |
| 19 | 427265435 |
| 20 | 1209664161 |
| 21 | 3424773601 |
| 22 | 9696140959 |
| 23 | 27451493281 |
| 24 | 77720042081 |
| 25 | 220039211683 |
| 26 | 622970000809 |
| 27 | 1763738467065 |
| 28 | 4993456147431 |