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Search: id:A107655
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| A107655 |
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a(n) is the smallest number m greater than 1 such that phi(m)=d(m)^n, where d(m) is number of positive divisors of m; if there is no such m, a(n)=1. |
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+0
2
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| 3, 5, 85, 17, 1285, 4369, 559876, 257, 327685, 1114129
(list; graph; listen)
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OFFSET
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0,1
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COMMENT
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For n=0,1,2,3 & 4 a(2^n)=F_n=A000215(n), where F_n is the n-th Fermat prime. Conjecture : a(11)=1.
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EXAMPLE
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a(10)=1114129 because phi(1114129)=d(1114129)^10 and 1114129 is the smallest number m greater than 1 that phi(m)=d(m)^10.
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CROSSREFS
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Cf. A000215, A033844.
Sequence in context: A122912 A062214 A144617 this_sequence A133660 A057663 A056244
Adjacent sequences: A107652 A107653 A107654 this_sequence A107656 A107657 A107658
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KEYWORD
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more,nonn
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AUTHOR
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Farideh Firoozbakht (mymontain(AT)yahoo.com), Jun 06 2005
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