OFFSET
1,2
COMMENTS
a(n) <= n (see Proposition 5.2 in Girard's paper, link below).
a(p) = 2, when p is prime.
LINKS
Altug Alkan, Table of n, a(n) for n = 1..10000
Benjamin Girard, On a combinatorial problem of Erdos, Kleitman and Lemke, arXiv:1010.5042 [math.CO], 2010-2012.
Benjamin Girard, On a combinatorial problem of Erdos, Kleitman and Lemke, Advances in Mathematics 231, 3-4 (2012) 1843-1857.
EXAMPLE
The divisors of 6 are : 1, 2, 3, 6; so a(6)=1/gpf(1)+2/gpf(2)+3/gpf(3)+6/gpf(6) = 1/1 + 2/2 + 3/3 + 6/3 = 5.
MATHEMATICA
a[n_] := Sum[d/FactorInteger[d][[-1, 1]], {d, Divisors[n]}];
Array[a, 80] (* Jean-François Alcover, Sep 26 2018 *)
PROG
(PARI) gpf(n) = {if (n==1, return (1), return (vecmax(factor(n)[, 1]))); }
a(n)= { my(d = divisors(n)); sum(j=1, length(d), d[j]/gpf(d[j])); } \\ revised by Michel Marcus, Sep 26 2018
CROSSREFS
KEYWORD
nonn
AUTHOR
Michel Marcus, Oct 14 2012
STATUS
approved