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A059428
Number of points of rotation in a prime block spiral.
1
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
OFFSET
1,1
COMMENTS
Analogous to A002620 except primes are substituted for the natural numbers.
FORMULA
Arrange primes in a block spiral formation. a(n) is determined by the point of rotation to allow for continuation of the sequence.
EXAMPLE
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)
MAPLE
A059428 := proc(n) RETURN(ithprime(1+floor(n^2/4))) end: # Francisco Salinas (franciscodesalinas(AT)hotmail.com), Jan 05 2002
CROSSREFS
Sequence in context: A073534 A063091 A124588 * A084571 A345471 A055498
KEYWORD
easy,nonn
AUTHOR
Jason Earls, Mar 15 2001
EXTENSIONS
More terms from Larry Reeves (larryr(AT)acm.org), Apr 19 2001
STATUS
approved