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 | 4 |
| 2 | 18 |
| 3 | 114 |
| 4 | 900 |
| 5 | 8845 |
| 6 | 103861 |
| 7 | 1427122 |
| 8 | 22486706 |
| 9 | 399906140 |
| 10 | 7922936720 |
| 11 | 173013117604 |
| 12 | 4127746294408 |
| 13 | 106806183646594 |
| 14 | 2978731438384738 |
| 15 | 89065499057526433 |
| 16 | 2842061902985159593 |
| 17 | 96395720127638538076 |
| 18 | 3462922846509648162418 |