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 | 1 |
| 2 | 3 |
| 3 | 9 |
| 4 | 57 |
| 5 | 417 |
| 6 | 4017 |
| 7 | 44337 |
| 8 | 568497 |
| 9 | 8188977 |
| 10 | 131568177 |
| 11 | 2326992177 |
| 12 | 44958134577 |
| 13 | 941649129777 |
| 14 | 21254190979377 |
| 15 | 514247427715377 |
| 16 | 13277149259395377 |
| 17 | 364340640790147377 |
| 18 | 10588931448837763377 |
| 19 | 324919870905259651377 |
| 20 | 10496883167091791491377 |