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A078784
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Primes on axis of Ulam square prime-spiral (with rows ... 7 8 9 / 6 1 2 / 5 4 3 /... ) with origin at (1).
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0
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2, 11, 19, 23, 53, 61, 127, 139, 151, 163, 233
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| Quadrants are numbered clockwise - 4 north, 1 east, 2 south, 3 west. The spiral numbers falling on axes (whether prime or not) are 4 North (2n+1)^2-n, 1 east (2n+1)^2+n+1, 2 south (2n)^2-(n-1), 3 west (2n)^2+n+1.
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EXAMPLE
| For example, n=0, quadrant = 1, a(1)=2, distance = 1 ex. n = 1, quadrant=1, a(2)=11, distance =2 ex. n=2, q=3, a(3)=19, distance = 2, ...
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CROSSREFS
| Sequence in context: A079062 A038930 A019375 * A117196 A064739 A112860
Adjacent sequences: A078781 A078782 A078783 * A078785 A078786 A078787
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KEYWORD
| nonn
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AUTHOR
| Donald S. McDonald (don.mcdonald(AT)paradise.net.nz), Jan 10 2003
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