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 A214666 The x-coordinates of prime numbers in an Ulam spiral oriented counterclockwise with first step west. 4

%I

%S -1,-1,1,1,-2,-2,2,2,0,-3,-3,3,3,3,-1,-4,-2,0,4,4,4,-2,-5,-5,1,5,5,5,

%T 5,3,-6,-6,-2,0,6,6,6,0,-4,-7,-7,-7,1,3,7,7,7,-5,-8,-8,-8,-8,-8,2,8,8,

%U 8,8,4,0,-2,-9,-9,-5,-3,1,9,9,5,3,-1,-7,-10,-10,-10

%N The x-coordinates of prime numbers in an Ulam spiral oriented counterclockwise with first step west.

%C The eight possible orientations of the Ulam spiral can be derived from combining either A214664 or A214666 with either A214665 or A214667 as ordered pairs of coordinates.

%C This spiral is rotated 180 degrees from the spiral on the March 1964 cover of Scientific American.

%H William Rex Marshall, <a href="/A214666/b214666.txt">Table of n, a(n) for n = 1..10077</a> (coordinates of primes in a 325 X 325 square)

%Y Cf. A000040, A063826, A214664, A214665, A214667.

%K sign,easy

%O 1,5

%A _William Rex Marshall_, Jul 26 2012

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Last modified May 12 20:41 EDT 2021. Contains 343829 sequences. (Running on oeis4.)