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A276663
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Sum of primes dividing n-th perfect number (with repetition).
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0
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5, 11, 39, 139, 8215, 131103, 524323, 2147483707, 2305843009213694071, 618970019642690137449562287, 162259276829213363391578010288339, 170141183460469231731687303715884105979
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OFFSET
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1,1
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COMMENTS
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Numbers that are equal to the sum of the prime factors (A001414) of some perfect number.
The next term is too large to include.
A001222(a(n)) is 1, 1, 2, 1, 3, 4, 2, 2, 4, 6, 7, 1, 11, ...
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LINKS
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FORMULA
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EXAMPLE
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39 is in this sequence because 39 - 2^(5 - 1) = 31 = 2^5 - 1 and 31 is prime.
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MATHEMATICA
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Table[Total[Times@@@FactorInteger[PerfectNumber[n]]], {n, 15}] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Sep 22 2019 *)
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PROG
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(PARI) \\ Ochem & Rao: no odd perfect numbers below 10^1500
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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