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A105365 Rearrangement of positive integers according to parity of (prime(n)-1)/2 (see comments). 1
1, 4, 2, 6, 8, 3, 5, 9, 10, 7, 12, 11, 13, 14, 15, 17, 16, 19, 18, 20, 23, 21, 22, 29, 31, 37, 24, 25, 41, 43, 26, 27, 47, 28, 53, 30, 59, 32, 33, 61, 34, 67, 35, 71, 73, 36, 38, 39, 40, 79, 83, 42, 89, 44, 97, 45, 101, 46, 103, 107 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

a(1)=1, for n>1: if (prime(n)-1)/2 is even/odd 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[OddQ[(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. A105366.

Sequence in context: A138947 A083412 A086399 * A077157 A268718 A306874

Adjacent sequences:  A105362 A105363 A105364 * A105366 A105367 A105368

KEYWORD

nonn

AUTHOR

Zak Seidov, Apr 01 2005

STATUS

approved

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Last modified February 18 04:48 EST 2020. Contains 332011 sequences. (Running on oeis4.)