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A059428
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Number of points of rotation in a prime block spiral.
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1
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2, 3, 5, 11, 17, 29, 41, 59, 73, 101, 127, 157, 191, 229, 269, 313, 367, 421, 467, 547, 607, 673, 751, 829, 919, 1013, 1093, 1201, 1297, 1429, 1523, 1621, 1753, 1889, 2027, 2153, 2309, 2441, 2621, 2749, 2909, 3089, 3299, 3463, 3623, 3821, 4007, 4217, 4421
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OFFSET
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1,1
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COMMENTS
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Analogous to A002620 except primes are substituted for the natural numbers.
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LINKS
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FORMULA
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Arrange primes in a block spiral formation. a(n) is determined by the point of rotation to allow for continuation of the sequence.
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EXAMPLE
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Spiral begins:
(73)-79--83--89--97-(101)
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71 (17)-19--23-(29) etc.
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67 13 (2)-(3) 31
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61 (11)--7--(5) 37
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(59)-53--47--43-(41)
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MAPLE
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A059428 := proc(n) RETURN(ithprime(1+floor(n^2/4))) end: # Francisco Salinas (franciscodesalinas(AT)hotmail.com), Jan 05 2002
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CROSSREFS
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KEYWORD
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easy,nonn
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AUTHOR
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EXTENSIONS
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More terms from Larry Reeves (larryr(AT)acm.org), Apr 19 2001
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STATUS
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approved
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