A177607 Number of permutations of 3 copies of 1..n avoiding adjacent step pattern up, down, down, down, up.
1, 1, 20, 1680, 359582, 156245130, 120386806922, 150097348110878, 283411248751268531
Offset: 0
Keywords
Crossrefs
Cf. A014606.
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.