cp's OEIS Frontend

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.

A097391 The number of hierarchies of n labeled elements with at least one subhierarchy composed of exactly 2 levels and no subhierarchy with more than 2 levels.

Table of values

n a(n)
1 0
2 1
3 3
4 8
5 17
6 37
7 71
8 138
9 252
10 458

List of values

[0, 1, 3, 8, 17, 37, 71, 138, 252, 458]