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 | 127 |
| 4 | 957 |
| 5 | 7497 |
| 6 | 60229 |
| 7 | 492483 |
| 8 | 4079826 |
| 9 | 34138873 |
| 10 | 287946771 |
| 11 | 2444458878 |
| 12 | 20863127251 |
| 13 | 178868929074 |
| 14 | 1539439262406 |
| 15 | 13293346718161 |
| 16 | 115123998810525 |
| 17 | 999553370761017 |
| 18 | 8698196146639573 |
| 19 | 75845560146124527 |
| 20 | 662551474429229571 |
| 21 | 5797239969198654748 |