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A214665
The y-coordinates of prime numbers in an Ulam spiral oriented counterclockwise with first step east.
20
0, 1, 1, -1, 0, 2, 2, 0, -2, 1, 3, 3, -1, -3, -3, 0, 4, 4, 2, -2, -4, -4, -3, 3, 5, 5, 3, -1, -3, -5, 0, 4, 6, 6, 2, 0, -6, -6, -6, -3, 3, 5, 7, 7, 7, 5, -7, -7, -6, -4, 0, 6, 8, 8, 8, 2, -4, -6, -8, -8, -8, -5, 9, 9, 9, 9, 3, -3, -9, -9, -9, -9, -4, 2, 8, 10
OFFSET
1,6
COMMENTS
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.
LINKS
William Rex Marshall, Table of n, a(n) for n = 1..10077 (coordinates of primes in a 325 X 325 square).
Scientific American, Front Matter, Vol. 210, No. 3, March 1964.
CROSSREFS
KEYWORD
sign,easy
AUTHOR
STATUS
approved