A105364 - OEIS

%I #3 Mar 30 2012 17:26:14

%S 2,1,4,6,3,5,8,10,7,12,9,11,14,16,13,18,15,20,22,17,24,26,19,21,23,28,

%T 30,25,27,32,34,29,36,31,38,33,40,42,35,44,37,46,39,41,48,50,52,54,43,

%U 45,56,47,58,49,60,51,62,53,55,64,57,66,68,59,61,70,63,72,65,67,74,76

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

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

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

%Y Cf. A105363.

%K nonn

%O 1,1

%A _Zak Seidov_, Apr 01 2005