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 | 9 |
| 2 | 63 |
| 3 | 399 |
| 4 | 2403 |
| 5 | 14067 |
| 6 | 80949 |
| 7 | 460845 |
| 8 | 2605590 |
| 9 | 14666470 |
| 10 | 82320714 |
| 11 | 461238282 |
| 12 | 2581644378 |
| 13 | 14442658074 |
| 14 | 80785970838 |
| 15 | 451934259654 |
| 16 | 2528977211775 |
| 17 | 14157983986839 |
| 18 | 79302044283297 |
| 19 | 444448115168049 |
| 20 | 2492468172937125 |