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Search: id:A077017
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| A077017 |
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a(1) = 2, a(n+1) = smallest positive integer divisible by the n-th prime that also has a nontrivial common divisor with a(n). |
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+0
3
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| 2, 2, 6, 10, 14, 22, 26, 34, 38, 46, 58, 62, 74, 82, 86, 94, 106, 118, 122, 134, 142, 146, 158, 166, 178, 194, 202, 206, 214, 218, 226, 254, 262, 274, 278, 298, 302, 314, 326, 334, 346, 358, 362, 382, 386, 394, 398, 422, 446, 454, 458, 466, 478, 482, 502, 514
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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Each term of the sequence is a solution of the equation sigma(x)=3*(x-phi(x)) (*) - the proof is easy. Does there exist a solution of (*) which is not in the sequence? - Farideh Firoozbakht (mymontain(AT)yahoo.com), Apr 22 2006
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FORMULA
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a(n) = 2*prime(n) for n>2.
a(n)=2*prime(n-1) for n>2. - Farideh Firoozbakht (mymontain(AT)yahoo.com), Apr 22 2006
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CROSSREFS
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Adjacent sequences: A077014 A077015 A077016 this_sequence A077018 A077019 A077020
Sequence in context: A077063 A081728 A080460 this_sequence A127404 A054227 A054228
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KEYWORD
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nonn,easy
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AUTHOR
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Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Oct 28 2002
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EXTENSIONS
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Corrected and extended by Dean Hickerson (dean(AT)math.ucdavis.edu), Jan 28 2003
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