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 | 1 |
| 3 | 4 |
| 4 | 10 |
| 5 | 28 |
| 6 | 75 |
| 7 | 202 |
| 8 | 540 |
| 9 | 1440 |
| 10 | 3828 |
| 11 | 10153 |
| 12 | 26875 |
| 13 | 71021 |
| 14 | 187421 |
| 15 | 494013 |
| 16 | 1300844 |
| 17 | 3422509 |
| 18 | 8998118 |
| 19 | 23642479 |
| 20 | 62088032 |
| 21 | 162978242 |
| 22 | 427648023 |
| 23 | 1121766397 |
| 24 | 2941697012 |
| 25 | 7712415568 |
| 26 | 20215976824 |
| 27 | 52981414253 |
| 28 | 138831400836 |