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) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 5 |
| 3 | 23 |
| 4 | 99 |
| 5 | 421 |
| 6 | 1785 |
| 7 | 7563 |
| 8 | 32039 |
| 9 | 135721 |
| 10 | 574925 |
| 11 | 2435423 |
| 12 | 10316619 |
| 13 | 43701901 |
| 14 | 185124225 |
| 15 | 784198803 |
| 16 | 3321919439 |
| 17 | 14071876561 |
| 18 | 59609425685 |
| 19 | 252509579303 |
| 20 | 1069647742899 |
| 21 | 4531100550901 |
| 22 | 19194049946505 |
| 23 | 81307300336923 |
| 24 | 344423251294199 |
| 25 | 1459000305513721 |
| 26 | 6180424473349085 |