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 | 1 |
| 2 | 6 |
| 3 | 21 |
| 4 | 104 |
| 5 | 452 |
| 6 | 2335 |
| 7 | 11992 |
| 8 | 66810 |
| 9 | 385101 |
| 10 | 2336352 |
| 11 | 14738380 |
| 12 | 96831730 |
| 13 | 659809115 |
| 14 | 4657075074 |
| 15 | 33974259046 |
| 16 | 255781455848 |
| 17 | 1984239830571 |
| 18 | 15839628564349 |
| 19 | 129951186405574 |
| 20 | 1094486382191624 |
| 21 | 9453318070371926 |
| 22 | 83654146992936350 |
| 23 | 757769011659766015 |
| 24 | 7020652591448497490 |