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 | 3 |
| 2 | 15 |
| 3 | 105 |
| 4 | 385 |
| 5 | 5005 |
| 6 | 85085 |
| 7 | 323323 |
| 8 | 7436429 |
| 9 | 30808063 |
| 10 | 955049953 |
| 11 | 35336848261 |
| 12 | 1448810778701 |
| 13 | 5663533044013 |
| 14 | 266186053068611 |
| 15 | 1085220062510491 |
| 16 | 64027983688118969 |
| 17 | 3905707004975257109 |
| 18 | 15393080549020130959 |
| 19 | 1092908718980429298089 |
| 20 | 79782336485571338760497 |