Search: id:A036913
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%I A036913
%S A036913 2,6,12,18,30,42,60,66,90,120,126,150,210,240,270,330,420,462,510,630,
%T A036913 660,690,840,870,1050,1260,1320,1470,1680,1890,2310,2730,2940,3150,
%U A036913 3570,3990,4620,4830,5460,5610,5670,6090,6930,7140,7350,8190,9240,9660
%N A036913 Sparsely totient numbers; numbers n such that m > n implies phi(m) > 
               phi(n).
%C A036913 The paper by Masser and Shiu lists 150 terms of this sequence less than 
               10^6. For odd prime p, they show that p# and p*p# are in this sequence, 
               where p# denotes the primorial (A002110). - T. D. Noe (noe(AT)sspectra.com), 
               Jun 14 2006
%D A036913 Glyn Harman, On sparsely totient numbers, Glasgow Math. J. 33 (1991), 
               349-358.
%H A036913 T. D. Noe, <a href="b036913.txt">Table of n, a(n) for n = 1..302</a>
%H A036913 Roger C. Baker and Glyn Harman, <a href="http://www.numdam.org/item?id=AFST_1996_6_5_2_183_0">
               Sparsely totient numbers</a>, Annales de la faculte des sciences 
               de Toulouse Ser. 6, 5 no. 2 (1996), 183-190.
%H A036913 D. W. Masser and P. Shiu, <a href="http://projecteuclid.org/Dienst/UI/
               1.0/Summarize/euclid.pjm/1102702441">On sparsely totient numbers</
               a>, Pacific J. Math. 121, no. 2 (1986), 407-426.
%e A036913 This sequence contains 60 because of all the numbers whose totient is 
               16, 60 is the largest such number. [From Graeme McRae (g_m(AT)mcraefamily.com), 
               Feb 12 2009]
%t A036913 nn=10000; lastN=Table[0,{nn}]; Do[e=EulerPhi[n]; If[e<=nn, lastN[[e]]=n], 
               {n,10nn}]; mx=0; lst={}; Do[If[lastN[[i]]>mx, mx=lastN[[i]]; AppendTo[lst,
               mx]], {i,Length[lastN]}]; lst - T. D. Noe (noe(AT)sspectra.com), 
               Jun 14 2006
%Y A036913 Cf. A097942 (highly totient numbers). Records in A006511 (see also A132154).
%Y A036913 Sequence in context: A159793 A006511 A113274 this_sequence A117311 A125024 
               A053660
%Y A036913 Adjacent sequences: A036910 A036911 A036912 this_sequence A036914 A036915 
               A036916
%K A036913 nonn
%O A036913 1,1
%A A036913 David W. Wilson (davidwwilson(AT)comcast.net)

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