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 | 13 |
| 4 | 73 |
| 5 | 167 |
| 6 | 4051 |
| 7 | 37633 |
| 8 | 43817 |
| 9 | 4596553 |
| 10 | 58941091 |
| 11 | 274691047 |
| 12 | 12470162233 |
| 13 | 202976401213 |
| 14 | 1178339174801 |
| 15 | 65573803186921 |
| 16 | 99264170666917 |
| 17 | 994319127823939 |
| 18 | 588633468315403843 |
| 19 | 13564373693588558173 |
| 20 | 109232642628695218147 |
| 21 | 752832094524169066031 |