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Search: id:A118700
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| A118700 |
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Odd n such that 2*phi(n) < n, but there does not exist even k < n with phi(k) = phi(n). |
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+0
4
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| 9075, 11985, 19965, 21165, 22515, 34935, 35445, 44505, 45315, 59415, 67431, 108927, 135945, 143451, 180999, 286425, 295659, 359499, 372945, 449445, 463845, 521157, 563295, 576045, 606879, 684411, 736695, 753225, 762105, 780549, 800565
(list; graph; listen)
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OFFSET
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1,1
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EXAMPLE
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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.
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PROGRAM
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(PARI) evenphimatch(n)=local(ph, i, r); ph=eulerphi(n); r=0; for(i=2*ph, n-1, 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)))
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CROSSREFS
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Cf. Members of A119434 not in A036798.
Adjacent sequences: A118697 A118698 A118699 this_sequence A118701 A118702 A118703
Sequence in context: A031773 A128374 A061135 this_sequence A097209 A015298 A093213
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KEYWORD
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nonn
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AUTHOR
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Frank Adams-Watters (FrankTAW(AT)Netscape.net), May 20 2006
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