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 | 4 |
| 2 | 9 |
| 3 | 29 |
| 4 | 97 |
| 5 | 340 |
| 6 | 1156 |
| 7 | 4068 |
| 8 | 14763 |
| 9 | 52950 |
| 10 | 190950 |
| 11 | 687442 |
| 12 | 2476661 |
| 13 | 8922447 |
| 14 | 32121858 |
| 15 | 115744464 |
| 16 | 416837976 |
| 17 | 1501406960 |
| 18 | 5406257970 |
| 19 | 19472791326 |
| 20 | 70130249296 |
| 21 | 252570497669 |
| 22 | 909559808019 |
| 23 | 3275792914936 |
| 24 | 11797588596607 |