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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.

A077550 Number of nonisomorphic ways a river (or undirected line) can cross two perpendicular roads n times (orbits of A076875 under symmetry group of order 8).

Table of values

n a(n)
0 1
1 1
2 2
3 3
4 9
5 21
6 54
7 131

List of values

[1, 1, 2, 3, 9, 21, 54, 131]

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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