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A074374 a(n) = sopfr(n)*(sopfr(n)+1)/2 where sopfr is the sum of the prime factors of n with repetition (A001414). 4
0, 0, 3, 6, 10, 15, 15, 28, 21, 21, 28, 66, 28, 91, 45, 36, 36, 153, 36, 190, 45, 55, 91, 276, 45, 55, 120, 45, 66, 435, 55, 496, 55, 105, 190, 78, 55, 703, 231, 136, 66, 861, 78, 946, 120, 66, 325, 1128, 66, 105, 78, 210, 153, 1431, 66, 136, 91, 253, 496, 1770, 78 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,3
LINKS
FORMULA
a(n) = A000217(A001414(n)).
EXAMPLE
a(10) = 7(7+1)/2 = 28 because 7 is the sum of the prime factors of 10.
MATHEMATICA
f[n_]:=Module[{c=Total[Times@@@FactorInteger[n]]}, (c(c+1))/2]; Join[{0, 0}, Array[f, 60, 2]] (* Harvey P. Dale, Aug 21 2011 *)
PROG
(PARI) s(n)=sum(i=1, omega(n), component(component(factor(n), 1), i)*component(component(factor(n), 2), i))); a(n)=s(n)*(s(n)+1)/2
CROSSREFS
Cf. A000217, A001414 (sopfr), A074372.
Sequence in context: A126234 A259604 A130484 * A109804 A231672 A120993
KEYWORD
easy,nonn
AUTHOR
W. Neville Holmes, Aug 29 2002
EXTENSIONS
More terms from Benoit Cloitre, Sep 02 2002
STATUS
approved

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Last modified July 19 22:34 EDT 2024. Contains 374441 sequences. (Running on oeis4.)