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 | 5 |
| 2 | 26 |
| 3 | 136 |
| 4 | 711 |
| 5 | 3716 |
| 6 | 19421 |
| 7 | 101501 |
| 8 | 530481 |
| 9 | 2772486 |
| 10 | 14490016 |
| 11 | 75730071 |
| 12 | 395792776 |
| 13 | 2068556381 |
| 14 | 10811024761 |
| 15 | 56502330541 |
| 16 | 295301641346 |
| 17 | 1543353319176 |
| 18 | 8066123361031 |
| 19 | 42156481777036 |
| 20 | 220325040452941 |
| 21 | 1151498450637621 |