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 | 25 |
| 2 | 119 |
| 3 | 445 |
| 4 | 1947 |
| 5 | 8575 |
| 6 | 38747 |
| 7 | 177223 |
| 8 | 819187 |
| 9 | 3816247 |
| 10 | 17891349 |
| 11 | 84312583 |
| 12 | 399037959 |
| 13 | 1895486995 |
| 14 | 9032061297 |
| 15 | 43155077395 |
| 16 | 206685100995 |
| 17 | 991968231607 |
| 18 | 4769763119885 |
| 19 | 22973188788967 |
| 20 | 110815066535017 |
| 21 | 535263089155897 |