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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 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 October 31 05:06 EDT 2020. Contains 338098 sequences. (Running on oeis4.)