

A140610


Running prime totals of prime factors (without multiplicity) of consecutive composite N.


1



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
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OFFSET

1,1


LINKS

Table of n, a(n) for n=1..43.


FORMULA

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.


EXAMPLE

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.


CROSSREFS

Cf. A140611.
Sequence in context: A334520 A308269 A038562 * A152461 A215208 A100119
Adjacent sequences: A140607 A140608 A140609 * A140611 A140612 A140613


KEYWORD

easy,nonn


AUTHOR

Enoch Haga, May 19 2008


STATUS

approved



