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Search: id:A068402
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| A068402 |
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Numbers n such that sigma(n+1)=n+phi(n). |
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+0
1
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| 4, 6, 32, 38, 54, 56, 84, 278, 2664, 10944, 15608, 20720, 84800, 179576, 209664, 6251904
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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Are there any odd values in the sequence?
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PROGRAM
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(PARI) : for(n=1, 500000, if(sigma(n+1)-n==eulerphi(n), print1(n, ", ")))
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CROSSREFS
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Sequence in context: A075590 A088255 A068720 this_sequence A078250 A087299 A164127
Adjacent sequences: A068399 A068400 A068401 this_sequence A068403 A068404 A068405
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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), Mar 02 2002
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EXTENSIONS
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One more term from Rick L. Shepherd (rshepherd2(AT)hotmail.com), Jun 21 2002
Any additional terms are greater than 20000000.
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