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A228181
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Numbers k such that sum of square of prime divisors of k equals sum of prime divisors of k+1.
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2
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12, 27, 385, 1120, 4840, 9936, 14500, 29440, 95795, 105875, 178904, 223155, 341248, 343343, 754985, 830908, 1059630, 1841049, 2408832, 2949375, 3564704, 4934358, 5368792, 5500312, 6695000, 6805372, 8332831, 8846656, 10126336, 12956040, 13157235, 17254600
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OFFSET
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1,1
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COMMENTS
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LINKS
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EXAMPLE
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The prime divisors of 9936 are {2, 3, 23} and the prime divisors of 9937 are {19, 523} => 2^2 + 3^2 + 23^2 = 19 + 523 = 542, hence 9936 is in the sequence.
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MATHEMATICA
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fQ[n_] := Plus @@ (First@# & /@ FactorInteger[n]^2) == Plus @@ (First@# & /@ FactorInteger[n + 1]); Select[ Range@ 100000, fQ]
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PROG
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(Magma) [k:k in [2..2500000]| &+PrimeDivisors(k+1) eq &+[PrimeDivisors(k)[i]^2: i in [1..#PrimeDivisors(k)]]]; // Marius A. Burtea, Feb 18 2020
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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