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 | 3 |
| 3 | 9 |
| 4 | 21 |
| 5 | 81 |
| 6 | 141 |
| 7 | 561 |
| 8 | 1401 |
| 9 | 3921 |
| 10 | 6441 |
| 11 | 34161 |
| 12 | 61881 |
| 13 | 422241 |
| 14 | 782601 |
| 15 | 1142961 |
| 16 | 1863681 |
| 17 | 14115921 |
| 18 | 26368161 |
| 19 | 259160721 |
| 20 | 491953281 |
| 21 | 724745841 |
| 22 | 957538401 |
| 23 | 6311767281 |
| 24 | 11665996161 |
| 25 | 38437140561 |
| 26 | 65208284961 |
| 27 | 145521718161 |
| 28 | 225835151361 |
| 29 | 2554924714161 |