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Search: id:A070994
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| A070994 |
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Numbers n such that the trajectory of n under the `3x+1' map reaches phi(n). |
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+0
1
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| 2, 3, 4, 5, 6, 8, 10, 11, 12, 15, 16, 17, 20, 22, 24, 25, 30, 32, 33, 34, 40, 41, 44, 47, 48, 50, 55, 59, 60, 64, 66, 71, 82, 85, 87, 88, 89, 94, 100, 107, 110, 118, 128, 132, 142, 164, 165, 170, 174, 178, 188, 214, 220, 235, 256, 328, 330, 340, 348, 376, 440, 470
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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If n is a power of 2, n is in the sequence.
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EXAMPLE
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trajectory of 10 is : (10,5,16,8,4,2,1) and phi(10)=4 is reached, hence 10 is in the sequence.
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PROGRAM
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(PARI) for(n=1, 10000, s=n; t=0; while(s!=1, t++; if(s%2==0, s=s/2, s=3*s+1); if(s==eulerphi(n), print1(n, ", "); ); ))
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CROSSREFS
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Sequence in context: A094942 A102705 A088232 this_sequence A057197 A067936 A087721
Adjacent sequences: A070991 A070992 A070993 this_sequence A070995 A070996 A070997
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KEYWORD
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easy,nonn
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AUTHOR
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Benoit Cloitre (benoit7848c(AT)orange.fr), May 18 2002
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