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A078182 a(n) = Sum_{d|n, d=2 mod 3} d. 16
0, 2, 0, 2, 5, 2, 0, 10, 0, 7, 11, 2, 0, 16, 5, 10, 17, 2, 0, 27, 0, 13, 23, 10, 5, 28, 0, 16, 29, 7, 0, 42, 11, 19, 40, 2, 0, 40, 0, 35, 41, 16, 0, 57, 5, 25, 47, 10, 0, 57, 17, 28, 53, 2, 16, 80, 0, 31, 59, 27, 0, 64, 0, 42, 70, 13, 0, 87, 23, 56, 71, 10, 0, 76, 5, 40, 88, 28, 0, 115 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Seiichi Manyama, Table of n, a(n) for n = 1..10000

FORMULA

G.f.: Sum_{n>=0} (3*n+2)*x^(3*n+2)/(1-x^(3*n+2)).

A078181(n) + a(n) + 3*A000203(n/3) = A000203(n), where A000203 is defined as zero for non-integer arguments. - R. J. Mathar, May 11 2016

MAPLE

A078182 := proc(n)

    a := 0 ;

    for d in numtheory[divisors](n) do

        if modp(d, 3) =2 then

            a :=a+d ;

        end if;

    end do:

    a;

end proc: # R. J. Mathar, May 11 2016

MATHEMATICA

a[n_] := Plus @@ Select[Divisors[n], Mod[#, 3] == 2 &]; Array[a, 100] (* Giovanni Resta, May 11 2016 *)

PROG

(PARI) a(n) = sumdiv(n, d, d*((d%3) == 2)); \\ Michel Marcus, May 11 2016

CROSSREFS

Cf. A001817, A001822, A035386, A078181, A272715.

Sequence in context: A344908 A005074 A161564 * A133394 A305628 A094721

Adjacent sequences:  A078179 A078180 A078181 * A078183 A078184 A078185

KEYWORD

easy,nonn

AUTHOR

Vladeta Jovovic, Nov 21 2002

STATUS

approved

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Last modified July 24 20:26 EDT 2021. Contains 346273 sequences. (Running on oeis4.)