OFFSET
1,4
LINKS
Seiichi Manyama, Table of n, a(n) for n = 1..10000
FORMULA
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 *)
PROG
(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
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Mar 21 2017
STATUS
approved