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) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 3 |
| 4 | 16 |
| 5 | 129 |
| 6 | 1438 |
| 7 | 20955 |
| 8 | 384226 |
| 9 | 8623101 |
| 10 | 231978454 |
| 11 | 7359117591 |
| 12 | 271673905642 |
| 13 | 11543742745689 |
| 14 | 559348370431630 |
| 15 | 30659822500574739 |
| 16 | 1887796293833267746 |
| 17 | 129757032076160998677 |
| 18 | 9900820197631733600518 |
| 19 | 834421415151529202479023 |
| 20 | 77318409826165250051727514 |