OFFSET
1,6
COMMENTS
Phi-summation over numbers not exceeding n are given in A002088, over divisor-set of n would give n, over RRS or unrelated numbers to n give newer values: at n=36 these values are {396,36,191,170}. This is a further way of Phi-summation.
LINKS
Michael De Vlieger, Table of n, a(n) for n = 1..10000
EXAMPLE
n=36 and its "unrelated-set" is {8,10,14,15,16,20,21,22,24,26,27,28,30,32,33,34} and their totients are {4,4,6,8,8,8,12,10,8,12,18,12,8,16,20,16}. The sum of these values is 170, so a(36)=170. For primes the unrelated set is empty and Phi-sum over empty set is 0.
MAPLE
A045763_row :=proc(n)
a := {} ;
dvs := numtheory[divisors](n) ;
for m from 2 to n-1 do
if igcd(m, n) >1 and not m in dvs then
a := a union {m} ;
end if;
end do:
a;
end proc:
A053571 := proc(n)
add(numtheory[phi](a), a=A045763_row(n)) ;
end proc: # R. J. Mathar, Jan 09 2017
MATHEMATICA
Table[Total@ EulerPhi@ Select[Range@ n, 1 < GCD[#, n] < # &], {n, 68}] (* Michael De Vlieger, Mar 05 2017 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Labos Elemer, Jan 17 2000
STATUS
approved
