The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A036798 Odd m such that there exists an even number k < m with phi(k) = phi(m). 11
 105, 165, 195, 315, 495, 525, 585, 735, 825, 945, 975, 1155, 1365, 1485, 1575, 1755, 1785, 1815, 1995, 2145, 2205, 2415, 2475, 2535, 2625, 2805, 2835, 2925, 3003, 3045, 3135, 3255, 3315, 3465, 3675, 3705, 3795, 3885, 3927, 4095, 4125, 4305, 4389, 4455 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS These numbers m appear to satisfy cototient(m) > totient(m) or 2*phi(m) < m; they seem to be the missing terms mentioned in A067800. - Labos Elemer, May 08 2003 All elements in this sequence must have 2*phi(m) < m, but not the reverse. See A118700. - Franklin T. Adams-Watters, May 21 2006 LINKS Robert Israel, Table of n, a(n) for n = 1..10000 MAPLE N:= 10^4: # to get all terms <= N PhiE:= map(numtheory:-phi, [seq(i, i=2..N, 2)]): A:= NULL: for n from 1 to N by 2 do t:= numtheory:-phi(n); if 2*t < n and member(t, PhiE[1..(n-1)/2]) then A:= A, n fi; od: A; # Robert Israel, Jan 06 2017 MATHEMATICA Select[ Range[1, 4483, 2], Mod[ #, EulerPhi[ # ]] != # - EulerPhi[ # ] &] (* Robert G. Wilson v, Jan 10 2004 *) CROSSREFS Cf. A000010, A067800, A083254. Cf. A091495 (Odd, squarefree n such that n/phi(n) > 2). Cf. A118700, A119434. Sequence in context: A152940 A189936 A076762 * A119434 A091495 A256673 Adjacent sequences: A036795 A036796 A036797 * A036799 A036800 A036801 KEYWORD nonn AUTHOR STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified February 6 04:21 EST 2023. Contains 360097 sequences. (Running on oeis4.)