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Search: id:A125841
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| A125841 |
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Numbers n such that previous_prime(n)=n-sd and next_prime(n)=n+sd where sd is sum of the distinct prime factors of n. |
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+0
2
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| 144, 288, 1728, 5184, 7168, 11760, 21632, 21952, 73500, 110592, 113400, 114244, 151263, 153790, 186624, 205800, 235298, 250563, 663552, 708588, 1404928, 2976750, 3449628, 4738500, 5265000, 7077888, 9437184, 11529602, 11745162
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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14267656658790241528591830756844692582808594415616 is a 50-digit term of this sequence. 493009335 is the smallest number n such that previous_prime(n)=n-s and next_prime(n)=n+s where s is sum of the prime factors of n. What is the next number with the same property?
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EXAMPLE
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113400=2^3*3^4*5^2*7 is in the sequence because previous_prime(113400)
=113400-(2+3+5+7) and next_prime(113400)=113400+(2+3+5+7).
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MATHEMATICA
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Do[If[c=Apply[Plus, PrimeFactorList[n]]; n-c==PreviousPrime[n]&&n+c== NextPrime[n], Print[n]], {n, 4, 20000000}]
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CROSSREFS
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Cf. A125840.
Sequence in context: A064563 A008436 A134341 this_sequence A154051 A030633 A034285
Adjacent sequences: A125838 A125839 A125840 this_sequence A125842 A125843 A125844
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KEYWORD
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easy,nonn
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AUTHOR
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Farideh Firoozbakht (mymontain(AT)yahoo.com), Feb 04 2007, corrected Feb 08 2007
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