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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.

A170807 Take the standard 2-D lattice packing of pennies; a(n) = number of ways to pick n pennies (modulo rotations and reflections) such that the graph with nodes = centers of pennies, edges = pairs of touching pennies is connected and every edge belongs to at least one triangle.

Table of values

n a(n)
1 1
2 0
3 1
4 1
5 2
6 4
7 7

List of values

[1, 0, 1, 1, 2, 4, 7]

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

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