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Search: id:A140610
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| A140610 |
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Running prime totals of prime factors (without multiplicity) of consecutive composite N. |
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+0
2
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| 2, 7, 19, 41, 43, 83, 103, 127, 233, 569, 673, 683, 1069, 1217, 1571, 2609, 2713, 2957, 3371, 3671, 3847, 3919, 4957, 4973, 6229, 7193, 7253, 7639, 8161, 8527, 9439, 9949, 10159, 12959, 13687, 13763, 13831, 13967, 15497, 16741, 17681, 17807, 20047
(list; graph; listen)
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OFFSET
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1,1
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FORMULA
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Compute prime factors (without multiplicity) of consecutive composite N. Maintain a running sum of these prime factors. Whenever the running total at N is prime, add to the sequence.
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EXAMPLE
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a(2)=7 because when N=6 the sum of composite prime factors is 7 and this total is prime (nonprime totals are not in this sequence). The prime factor (without multiplicity) of the first composite 4 is 2; the second composite is 6 with prime factors 3 and 2, so 2+2+3=7, the prime sum of prime factors at N=6.
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CROSSREFS
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Cf. A140611.
Adjacent sequences: A140607 A140608 A140609 this_sequence A140611 A140612 A140613
Sequence in context: A038952 A034794 A038562 this_sequence A100119 A078842 A110299
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KEYWORD
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easy,nonn
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AUTHOR
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Enoch Haga (Enokh(AT)comcast.net), May 19 2008
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