A105363 Rearrangement of positive integers according to parity of (prime(n)-1)/2 (see comments).

1, 2, 3, 5, 4, 6, 7, 9, 8, 11, 10, 12, 13, 15, 14, 17, 16, 19, 21, 18, 23, 25, 20, 22, 24, 27, 29, 26, 28, 31, 33, 30, 35, 32, 37, 34, 39, 41, 36, 43, 38, 45, 40, 42, 47, 49, 51, 53, 44, 46, 55, 48, 57, 50, 59, 52, 61, 54, 56, 63, 58, 65, 67, 60, 62, 69, 64, 71, 66, 68, 73, 75

Offset

1,2

Comments

If (prime(n+1)-1)/2 is even/odd then a(n) is the next even/odd number.

Links

Table of n, a(n) for n=1..72.

Mathematica

bb={}; od=-1; ev=0; Do[If[EvenQ[(Prime[i]-1)/2], ev=ev+2; bb=Append[bb, ev], od=od+2; bb=Append[bb, od]], {i, 2, 200}]; bb

Crossrefs

Cf. A105364.

Sequence in context: A299237 A257676 A257677 * A279337 A279336 A275375

Adjacent sequences: A105360 A105361 A105362 * A105364 A105365 A105366

Keyword

nonn

Author

Zak Seidov, Apr 01 2005

Status

approved