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A335341 Sum of divisors of A003557(n). 4
1, 1, 1, 3, 1, 1, 1, 7, 4, 1, 1, 3, 1, 1, 1, 15, 1, 4, 1, 3, 1, 1, 1, 7, 6, 1, 13, 3, 1, 1, 1, 31, 1, 1, 1, 12, 1, 1, 1, 7, 1, 1, 1, 3, 4, 1, 1, 15, 8, 6, 1, 3, 1, 13, 1, 7, 1, 1, 1, 3, 1, 1, 4, 63, 1, 1, 1, 3, 1, 1, 1, 28, 1, 1, 6, 3, 1, 1, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

LINKS

Antti Karttunen, Table of n, a(n) for n = 1..16383

Antti Karttunen, Data supplement: n, a(n) computed for n = 1..65537

FORMULA

a(n) = A000203(A003557(n)).

Multiplicative with a(p^1)=1 and a(p^e) = (p^e-1)/(p-1) if e>1.

A057723(n) = A007947(n)*a(n).

a(n) = 1 iff n in A005117.

a(n) = A336567(n) + A003557(n). - Antti Karttunen, Jul 28 2020

MAPLE

A335341 := proc(n)

    local a, pe, p, e ;

    a := 1;

    for pe in ifactors(n)[2] do

        p := op(1, pe) ;

        e := op(2, pe) ;

        if e > 1 then

            a := a*(p^e-1)/(p-1) ;

        end if;

    end do:

    a ;

end proc:

MATHEMATICA

f[p_, e_] := (p^e-1)/(p-1); a[1] = 1; a[n_] := Times @@ f @@@ FactorInteger[n]; Array[a, 100] (* Amiram Eldar, Sep 26 2020 *)

PROG

(PARI) a(n) = sigma(n/factorback(factor(n)[, 1])); \\ Michel Marcus, Jun 02 2020

CROSSREFS

Cf. A000203, A003557, A005361 (number of divisors of A003557), A336567.

Sequence in context: A152884 A263756 A204984 * A243473 A325969 A325826

Adjacent sequences:  A335338 A335339 A335340 * A335342 A335343 A335344

KEYWORD

nonn,mult,easy

AUTHOR

R. J. Mathar, Jun 02 2020

STATUS

approved

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Last modified August 5 14:57 EDT 2021. Contains 346469 sequences. (Running on oeis4.)