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Search: id:A063444
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| A063444 |
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Smallest number such that GCD of EulerPhi of 2 consecutive integer equals 2n. |
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+0
2
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| 3, 12, 13, 15, 121, 35, 86, 64, 37, 99, 726, 72, 158, 196, 61, 96, 4931, 73, 7639, 175, 343, 267, 2302, 104, 250, 676, 162, 637, 3481, 154, 21142, 192, 2178, 411, 5041, 814, 446, 1145, 157, 164, 6971, 1348, 14878, 1334, 542, 2115, 22090, 193, 2842, 2200
(list; graph; listen)
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OFFSET
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1,1
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LINKS
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Harry J. Smith, Table of n, a(n) for n=1,...,350
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FORMULA
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Min{x; GCD[Phi[x+1], Phi[x]]=2n}=Min{x; A058515[x]=2n}
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EXAMPLE
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n = 10, a(10) = 99, Phi(99) = 60, Phi(100) = 40, GCD[60,40] = 2n = 20.
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PROGRAM
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(PARI) { for (n=1, 350, x=1; while (gcd(eulerphi(x+1), eulerphi(x)) != 2*n, x++); write("b063444.txt", n, " ", x) ) } [From Harry J. Smith (hjsmithh(AT)sbcglobal.net), Aug 21 2009]
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CROSSREFS
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A000010, A058515.
Sequence in context: A085060 A024546 A073542 this_sequence A117061 A089919 A032918
Adjacent sequences: A063441 A063442 A063443 this_sequence A063445 A063446 A063447
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KEYWORD
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nonn
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AUTHOR
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Labos E. (labos(AT)ana.sote.hu), Jul 24 2001
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