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A235323
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Squared sum of the distinct prime factors of n, i.e., sopf(n)^2.
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1
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0, 4, 9, 4, 25, 25, 49, 4, 9, 49, 121, 25, 169, 81, 64, 4, 289, 25, 361, 49, 100, 169, 529, 25, 25, 225, 9, 81, 841, 100, 961, 4, 196, 361, 144, 25, 1369, 441, 256, 49, 1681, 144, 1849, 169, 64, 625, 2209, 25, 49, 49, 400, 225, 2809, 25, 256, 81, 484, 961
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OFFSET
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1,2
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COMMENTS
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If n is a prime power p^e, A000961, then a(n) = p^2.
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LINKS
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FORMULA
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EXAMPLE
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a(5) = 25; The only prime factor of 5 is just 5, and so 5^2 = 25.
a(6) = 25; The sum of the prime factors of 6 = 2*3 is 2+3 = 5, and 5^2 = 25.
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MATHEMATICA
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Prepend[Array[Plus @@ First[Transpose[FactorInteger[#]]]^2 &, 100, 2],
0]
Join[{0}, Table[Total[FactorInteger[n][[All, 1]]]^2, {n, 2, 60}]] (* Harvey P. Dale, Feb 10 2019 *)
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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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