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 | 77 |
| 5 | 587 |
| 6 | 5484 |
| 7 | 60582 |
| 8 | 771261 |
| 9 | 11102828 |
| 10 | 178144861 |
| 11 | 3149976426 |
| 12 | 60825085447 |
| 13 | 1273060083700 |
| 14 | 28700081677767 |
| 15 | 693217471426114 |
| 16 | 17857152401368800 |
| 17 | 488620956679818191 |
| 18 | 14152040894854881662 |
| 19 | 432509671322583878614 |
| 20 | 13908794132963653028146 |