Talk:Odd composites

One Subset

Of general interest I think would be those members with adjacency to multiples of 6 (some are 25,35,49,55,65 ). An interesting aspect is what % of the odd composites does this subset constitute? It increases to ~ 29+%, it may be tending towards a limit, I am not sure. It reaches 29% by n= 38,000,000. The Pari code I used was:

genit(maxx)={tcnt=0;acnt=0;for(n=9,maxx,if(!isprime(n),tcnt+=1;if(n%6==1||n%6==5,acnt+=1));if(n%1000000==0,print (n," ", 1.*acnt/tcnt ))) ;print (1.*acnt/tcnt);}

At the limit, 100% of odd numbers are composite. Odd numbers are either congruent to 1, 3 or 5 (mod 6), thus 2/3 of odd composites are congruent to 1 or 5 (mod 6). Each of the three congruence classes contains 1/3 of the odd composites. — Daniel Forgues 21:25, 2 July 2016 (UTC)