A385616 Indices of pentagonal numbers that are one-fifth of another one.
0, 1, 39, 85705, 4026303, 8886048529, 417455130327, 921323283480793, 43282582818520431, 95524640668969514017
Offset: 1
Crossrefs
Cf. A385152.
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.