# Greetings from The On-Line Encyclopedia of Integer Sequences! http://oeis.org/ Search: id:a176598 Showing 1-1 of 1 %I A176598 #12 May 16 2013 02:06:05 %S A176598 410,820,1640,2050,3280,4100,6560,8200,10250,13120,16400,16810,20500, %T A176598 26240,32800,33620,41000,51250,52480,65600,67240,82000,84050,102500, %U A176598 104960,131200,134480,164000,168100,205000,209920,256250,262400,268960,328000,336200 %N A176598 Numbers n such that phi(n)/n = 16/41. %C A176598 Phi(.)= A000010(.) is the Euler totient function. %D A176598 J.-M. De Koninck, Ces nombres qui nous fascinent, Entry 410, p. 91, Ellipses, Paris 2008. %H A176598 Donovan Johnson, Table of n, a(n) for n = 1..500 %H A176598 H. Fripertinger, The Euler phi function %H A176598 Wikipedia, Euler's totient function %F A176598 41n < a(n) <= 205 * 2^n. - _Charles R Greathouse IV_, May 15 2013 %e A176598 For n = 410, phi(410)/410 = 160/410 = 16/41, which puts 410 into the sequence. %p A176598 with(numtheory): ii:=1: N0:=40: tabl:=array(1..N0+1): for n from 1 to 540000 do : if 41*phi(n)=16*n then tabl[ii]:= n: ii:= ii+1: fi: od: print(tabl): %o A176598 (PARI) is(n)=eulerphi(n)/n==16/41 \\ _Charles R Greathouse IV_, May 15 2013 %Y A176598 Cf. A172344. %K A176598 nonn %O A176598 1,1 %A A176598 _Michel Lagneau_, Apr 21 2010 %E A176598 Link to b-file of another sequence removed - _R. J. Mathar_, Oct 20 2010 # Content is available under The OEIS End-User License Agreement: http://oeis.org/LICENSE