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 | 19 |
| 3 | 138 |
| 4 | 1072 |
| 5 | 8661 |
| 6 | 71758 |
| 7 | 605094 |
| 8 | 5169286 |
| 9 | 44605527 |
| 10 | 387969346 |
| 11 | 3396331158 |
| 12 | 29891385937 |
| 13 | 264264469542 |
| 14 | 2345319267553 |
| 15 | 20883723678234 |
| 16 | 186497307222706 |
| 17 | 1669724703219384 |
| 18 | 14983025158691938 |
| 19 | 134719748524295094 |
| 20 | 1213531265862339751 |