A118700 Odd n such that 2*phi(n) < n, but there does not exist an even k < n with phi(k) = phi(n).

9075, 11985, 19965, 21165, 22515, 22815, 34935, 35445, 44505, 45315, 59415, 67431, 67545, 108927, 135945, 143451, 180999, 286425, 295659, 359499, 360315, 372945, 449445, 463845, 521157, 563295, 576045, 606879, 607905, 684411, 736695, 753225, 762105, 780549, 800565

Offset: 1

Author

Franklin T. Adams-Watters, May 20 2006

Keywords

• nonn

Examples

			105 is the smallest odd number such that 2*phi(n) < n, but phi(105) = 48 = phi(104), so 105 is not in the sequence.
		

Links

• Donovan Johnson, Table of n, a(n) for n = 1..1000

Crossrefs

Members of A119434 not in A036798.

Programs

PARI

evenphimatch(n)=local(ph,i,r);ph=eulerphi(n);r=0;forstep(i=2*ph,n-1,2,if(eulerphi(i)==ph,r=i;break));r
nextoddlowphi(n)=while(2*eulerphi(n)>n,n+=2);n
i=1;while(i<1000000,i=nextoddlowphi(i+2);if(evenphimatch(i)==0,print(i)))