A284150 Sum_{d|n, d==1 or 4 mod 5} d.

1, 1, 1, 5, 1, 7, 1, 5, 10, 1, 12, 11, 1, 15, 1, 21, 1, 16, 20, 5, 22, 12, 1, 35, 1, 27, 10, 19, 30, 7, 32, 21, 12, 35, 1, 56, 1, 20, 40, 5, 42, 42, 1, 60, 10, 47, 1, 51, 50, 1, 52, 31, 1, 70, 12, 75, 20, 30, 60, 11, 62, 32, 31, 85, 1, 84, 1, 39, 70, 15, 72, 80, 1

Offset: 1

Author

Seiichi Manyama, Mar 21 2017

Keywords

• nonn

Links

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

Crossrefs

Cf. A003114, A284097, A284103.

Cf. Sum_{d|n, d==1 or k-1 mod k} d: A046913 (k=3), A000593 (k=4), this sequence (k=5), A186099 (k=6), A284151 (k=7).

Programs

Maple

A284150 := proc(n)
    a := 0 ;
    for d in numtheory[divisors](n) do
        if modp(d,5) in {1,4} then
            a := a+d ;
        end if;
    end do:
    a ;
end proc: # R. J. Mathar, Mar 21 2017

Mathematica

Table[Sum[If[Mod[d, 5] == 1 || Mod[d,5]==4, d, 0], {d, Divisors[n]}], {n, 80}] (* Indranil Ghosh, Mar 21 2017 *)

PARI

for(n=1, 80, print1(sumdiv(n, d, if(d%5==1 || d%5 ==4, d, 0)), ", ")) \\ Indranil Ghosh, Mar 21 2017

Python

from sympy import divisors
def a(n): return sum([d for d in divisors(n) if d%5==1 or d%5 == 4]) # Indranil Ghosh, Mar 21 2017

Formula

a(n) = A284097(n) + A284103(n). - Seiichi Manyama, Mar 24 2017