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A239546
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Sum of the prime factors of n, where n runs through perfect numbers.
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1
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5, 9, 33, 129, 8193, 131073, 524289, 2147483649, 2305843009213693953, 618970019642690137449562113, 162259276829213363391578010288129, 170141183460469231731687303715884105729
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OFFSET
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1,1
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LINKS
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FORMULA
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EXAMPLE
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First perfect number is 6, its two prime factors are 2 and 3, so a(1) = 5.
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MATHEMATICA
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perf=(# (#+1))/2&/@Select[2^Range[1000]-1, PrimeQ];
spf[n_]:=Total[First/@FactorInteger[n]]; spf/@perf (* Ivan N. Ianakiev, Jul 11 2015 *)
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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