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) |
|---|---|
| 4 | 1 |
| 5 | 1 |
| 6 | 4 |
| 7 | 15 |
| 8 | 64 |
| 9 | 293 |
| 10 | 1414 |
| 11 | 7102 |
| 12 | 36809 |
| 13 | 195676 |
| 14 | 1062176 |
| 15 | 5867676 |
| 16 | 32901124 |
| 17 | 186866589 |
| 18 | 1073261418 |
| 19 | 6225028476 |
| 20 | 36420849235 |
| 21 | 214744648169 |
| 22 | 1275005642668 |
| 23 | 7617704400227 |
| 24 | 45772485843616 |
| 25 | 276460659973100 |
| 26 | 1677717692649544 |
| 27 | 10225697003966360 |
| 28 | 62575895785795084 |