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 | 1 |
| 3 | 3 |
| 4 | 9 |
| 5 | 21 |
| 6 | 111 |
| 7 | 393 |
| 8 | 2309 |
| 9 | 12321 |
| 10 | 81071 |
| 11 | 560033 |
| 12 | 4301109 |
| 13 | 35526921 |
| 14 | 316858231 |
| 15 | 3025055673 |
| 16 | 30815437909 |
| 17 | 333492212321 |
| 18 | 3821573586591 |
| 19 | 46224758487313 |
| 20 | 588552491006709 |
| 21 | 7868364598774521 |
| 22 | 110201454736846151 |
| 23 | 1613597716238974953 |
| 24 | 24653957361927031509 |