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A358077
Sum of the nonprime divisors of n whose divisor complement is squarefree.
0
1, 1, 1, 4, 1, 7, 1, 12, 9, 11, 1, 22, 1, 15, 16, 24, 1, 33, 1, 34, 22, 23, 1, 48, 25, 27, 36, 46, 1, 62, 1, 48, 34, 35, 36, 72, 1, 39, 40, 72, 1, 84, 1, 70, 69, 47, 1, 96, 49, 85, 52, 82, 1, 108, 56, 96, 58, 59, 1, 142, 1, 63, 93, 96, 66, 128, 1, 106, 70, 130, 1, 144, 1, 75
OFFSET
1,4
FORMULA
a(n) = Sum_{d|n, nonprime d, n/d squarefree} d.
EXAMPLE
a(8) = 12. The nonprime divisors of 8 whose divisor complements are squarefree are 4 and 8 and their sum is 12.
MATHEMATICA
a[n_] := DivisorSum[n, # &, ! PrimeQ[#] && SquareFreeQ[n/#] &]; Array[a, 100] (* Amiram Eldar, Oct 30 2022 *)
PROG
(PARI) a(n) = sumdiv(n, d, if (!isprime(d) && issquarefree(n/d), d)); \\ Michel Marcus, Oct 30 2022
CROSSREFS
Sequence in context: A065814 A329347 A348981 * A340073 A050356 A245838
KEYWORD
nonn
AUTHOR
Wesley Ivan Hurt, Oct 29 2022
STATUS
approved