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 | 10 |
| 3 | 36 |
| 4 | 135 |
| 5 | 513 |
| 6 | 1944 |
| 7 | 7290 |
| 8 | 26973 |
| 9 | 98415 |
| 10 | 354294 |
| 11 | 1259712 |
| 12 | 4428675 |
| 13 | 15411789 |
| 14 | 53144100 |
| 15 | 181752822 |
| 16 | 617003001 |
| 17 | 2080591515 |
| 18 | 6973568802 |
| 19 | 23245229340 |
| 20 | 77096677311 |
| 21 | 254535261273 |
| 22 | 836828256240 |
| 23 | 2740612539186 |