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 | 6 |
| 2 | 21 |
| 3 | 75 |
| 4 | 274 |
| 5 | 989 |
| 6 | 3579 |
| 7 | 12964 |
| 8 | 46952 |
| 9 | 170076 |
| 10 | 616065 |
| 11 | 2231527 |
| 12 | 8083084 |
| 13 | 29278684 |
| 14 | 106053662 |
| 15 | 384149029 |
| 16 | 1391469865 |
| 17 | 5040201168 |
| 18 | 18256685634 |
| 19 | 66129616610 |
| 20 | 239535602559 |
| 21 | 867649138787 |
| 22 | 3142810588438 |
| 23 | 11383931537547 |
| 24 | 41235032657415 |