A105366 Rearrangement of positive integers according to parity of (prime(n)-1)/2 (see comments).

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

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