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 | 2 |
| 3 | 7 |
| 4 | 42 |
| 5 | 376 |
| 6 | 4513 |
| 7 | 68090 |
| 8 | 1238968 |
| 9 | 26416729 |
| 10 | 646140364 |
| 11 | 17837852044 |
| 12 | 548713088399 |
| 13 | 18612963873492 |
| 14 | 690271321314292 |
| 15 | 27785827303491579 |
| 16 | 1206582732097720126 |
| 17 | 56224025231569020724 |
| 18 | 2798445211000659147033 |
| 19 | 148178324442139816854902 |
| 20 | 8317074395027724691495980 |