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Search: id:A161962
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| A161962 |
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Odd numbers n such that phi(n)<phi(n+1). |
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+0
1
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| 105, 165, 315, 525, 585, 735, 1155, 1365, 1485, 1575, 1755, 1785, 1815, 1995, 2145, 2205, 2415, 2475, 2535, 2805, 2835, 3003, 3045, 3315, 3465, 3675, 3885, 3927, 4095, 4125, 4305, 4455, 4485, 4515, 4725, 4785, 4845, 4935, 5115, 5145
(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 even then for obvious reasons phi(n) will usually be less than phi(n+1). So it is more interesting to see when this occurs for odd n.
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EXAMPLE
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105 is in this list since phi(105)=48 and phi(106)=52.
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MAPLE
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with(numtheory): a := proc (n) if `mod`(n, 2) = 1 and phi(n) < phi(n+1) then n else end if end proc: seq(a(n), n = 1 .. 6000); [From Emeric Deutsch (deutsch(AT)duke.poly.edu), Jul 11 2009]
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CROSSREFS
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Sequence in context: A046405 A128278 A128284 this_sequence A046887 A026066 A167629
Adjacent sequences: A161959 A161960 A161961 this_sequence A161963 A161964 A161965
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KEYWORD
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easy,nonn
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AUTHOR
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David Angell (angell(AT)maths.unsw.edu.au), Jun 22 2009
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