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A105366 Rearrangement of positive integers according to parity of (prime(n)-1)/2 (see comments). 1
1, 2, 4, 3, 5, 6, 8, 7, 11, 9, 13, 10, 12, 17, 19, 14, 23, 15, 29, 31, 16, 37, 41, 18, 20, 21, 43, 47, 22, 24, 53, 59, 25, 61, 26, 67, 27, 71, 73, 28, 79, 30, 83, 32, 33, 89, 97, 101, 103, 34, 35, 107, 36, 109, 38, 113, 39, 127, 40, 42 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

a(1)=1, for n>1: if (prime(n)-1)/2 is odd/even then a(n) is the next prime/composite number.

LINKS

Table of n, a(n) for n=1..60.

MATHEMATICA

p=Prime[Range[100]]; s=Complement[Range[100], p]; bb={1}; is=1; ip=0; Do[If[EvenQ[(Prime[i]-1)/2], is=is+1; bb=Append[bb, s[[is]]], ip=ip+1; bb=Append[bb, p[[ip]]]], {i, 2, 60}]; bb

CROSSREFS

Cf. A105365.

Sequence in context: A075618 A095689 A083194 * A077156 A258076 A244724

Adjacent sequences:  A105363 A105364 A105365 * A105367 A105368 A105369

KEYWORD

nonn

AUTHOR

Zak Seidov, Apr 01 2005

STATUS

approved

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Last modified July 30 07:49 EDT 2021. Contains 346348 sequences. (Running on oeis4.)