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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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Analogous to A002620 except primes are substituted for the natural numbers.

LINKS

Table of n, a(n) for n=1..49.

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)

..|......................|

.71..(17)-19--23--(29) etc.

..|....|............|

.67...13..(2)-(3)..31

..|....|.......|....|

.61..(11)--7--(5)..37

..|.................|

(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 A055498 A073021

Adjacent sequences:  A059425 A059426 A059427 * A059429 A059430 A059431

KEYWORD

easy,nonn

AUTHOR

Jason Earls, Mar 15 2001

EXTENSIONS

More terms from Larry Reeves (larryr(AT)acm.org), Apr 19 2001

STATUS

approved

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Last modified November 15 03:42 EST 2018. Contains 317225 sequences. (Running on oeis4.)