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 | 5 |
| 3 | 25 |
| 4 | 157 |
| 5 | 1265 |
| 6 | 12661 |
| 7 | 151945 |
| 8 | 2127245 |
| 9 | 34035937 |
| 10 | 612646885 |
| 11 | 12252937721 |
| 12 | 269564629885 |
| 13 | 6469551117265 |
| 14 | 168208329048917 |
| 15 | 4709833213369705 |
| 16 | 141294996401091181 |
| 17 | 4521439884834917825 |
| 18 | 153728956084387206085 |
| 19 | 5534242419037939419097 |
| 20 | 210301211923441697925725 |