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 | 4 |
| 3 | 24 |
| 4 | 148 |
| 5 | 1180 |
| 6 | 10428 |
| 7 | 106876 |
| 8 | 1198160 |
| 9 | 14843808 |
| 10 | 198832320 |
| 11 | 2877693984 |
| 12 | 44545268832 |
| 13 | 734929736736 |
| 14 | 12852051257472 |
| 15 | 237372559264320 |
| 16 | 4614124211454720 |
| 17 | 94103610003019008 |
| 18 | 2008507968212696064 |
| 19 | 44748953208031094784 |
| 20 | 1038646472528272158720 |