data/problems/265.yml
---
:id: 265
:name: Binary Circles
:url: https://projecteuler.net/problem=265
:content: "2<sup>N</sup> binary digits can be placed in a circle so that all the N-digit
clockwise subsequences are distinct.\n\nFor N=3, two such circular arrangements
are possible, ignoring rotations:\n\n ![p265_BinaryCircles.gif]({{ images_dir }}/p265_BinaryCircles.gif)\n\nFor
the first arrangement, the 3-digit subsequences, in clockwise order, are: \n 000,
001, 010, 101, 011, 111, 110 and 100.\n\nEach circular arrangement can be encoded
as a number by concatenating the binary digits starting with the subsequence of
all zeros as the most significant bits and proceeding clockwise. The two arrangements
for N=3 are thus represented as 23 and 29:\n\n00010111 <sub>2</sub> = 23\n\n00011101 <sub>2</sub>
= 29\n\nCalling S(N) the sum of the unique numeric representations, we can see that
S(3) = 23 + 29 = 52.\n\nFind S(5).\n\n"