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 | 1 |
| 1 | 3 |
| 2 | 18 |
| 3 | 133 |
| 4 | 1095 |
| 5 | 9636 |
| 6 | 88718 |
| 7 | 843993 |
| 8 | 8230671 |
| 9 | 81841987 |
| 10 | 826641816 |
| 11 | 8457710604 |
| 12 | 87472494564 |
| 13 | 912995025912 |
| 14 | 9604763388534 |
| 15 | 101736967518497 |
| 16 | 1084125909550959 |
| 17 | 11614159795566489 |
| 18 | 125011746270524690 |
| 19 | 1351312626871871661 |
| 20 | 14662950224977228047 |