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Search: id:A117103
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| A117103 |
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Let p = n-th prime. Then a(n) = least odd composite number m such that nextprime(p*m) > p*nextprime(m). |
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1
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| 27, 39, 105, 279, 629, 597, 1661, 1875, 3777, 13961, 15491, 33585, 87401, 11445, 28877, 113451, 265115, 146189, 584705, 668525, 1370667, 1582581, 1471865, 2193351, 2932901, 3832635, 3571617, 3617721, 15131459, 31245831, 11442269
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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If k is prime then nextprime(k)=k.
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LINKS
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Ray Chandler, Table of n, a(n) for n=1..32
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EXAMPLE
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For n = 1, p=2, least odd composite m such than f(2*m)>2*f(m) is 27=a(1).
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PROGRAM
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(PARI) f(n)=nextprime(n); g(n, a)=for(i=1, a, if(f(n*i)>f(n)*f(i) && !isprime(i) && Mod(i, 2)!=0, return(i))); forprime (i=1, 150, print1(g(i, 500000000), ", "))
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CROSSREFS
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Adjacent sequences: A117100 A117101 A117102 this_sequence A117104 A117105 A117106
Sequence in context: A069105 A097228 A039614 this_sequence A124940 A114446 A141229
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KEYWORD
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nonn
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AUTHOR
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Mohammed Bouayoun (mohammed.bouayoun(AT)sanef.com), Apr 18 2006
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EXTENSIONS
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a(26)-a(30) from Zak Seidov (zakseidov(AT)yahoo.com), May 15 2007
a(31)-a(32) from Ray Chandler (rayjchandler(AT)sbcglobal.net), May 30 2007
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