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 | 0 |
| 1 | 1 |
| 2 | 513 |
| 3 | 29526 |
| 4 | 524290 |
| 5 | 4882815 |
| 6 | 30233091 |
| 7 | 141237628 |
| 8 | 536870916 |
| 9 | 1743392205 |
| 10 | 5000000005 |
| 11 | 12968712306 |
| 12 | 30958682118 |
| 13 | 68929245931 |
| 14 | 144627327495 |
| 15 | 288325195320 |
| 16 | 549755813896 |
| 17 | 1007996950233 |
| 18 | 1785233613321 |
| 19 | 3065533128910 |
| 20 | 5120000000010 |
| 21 | 8339940489111 |