A211932 a(n) = Sum_{ m=1..n and gcd(n,m)>1 } tau(m), where tau is the number of divisors function, A000005.

0, 2, 2, 5, 2, 11, 2, 13, 9, 19, 2, 28, 2, 29, 25, 32, 2, 47, 2, 50, 35, 50, 2, 69, 19, 62, 41, 72, 2, 96, 2, 80, 59, 86, 47, 114, 2, 99, 72, 118, 2, 144, 2, 125, 107, 125, 2, 164, 31, 158, 100, 151, 2, 188, 71, 174, 112, 167, 2, 229, 2, 183, 151, 188, 87, 247, 2, 208, 142, 252, 2, 271, 2, 228, 203, 238, 85

Offset: 1

Author

Naohiro Nomoto, Aug 05 2012

Keywords

• nonn
• easy

Links

• Antti Karttunen, Table of n, a(n) for n = 1..20000

Crossrefs

Cf. A000005, A143615.

Programs

Maple

A211932 := proc(n)
        local a,m;
        a := 0 ;
        for m from 1 to n do
                if gcd(m,n) > 1 then
                a := a+numtheory[tau](m) ;
                end if;
        end do:
        a ;
end proc: # R. J. Mathar, Aug 08 2012

PARI

A211932(n) = sum(m=1,n,if(1==gcd(n,m),0,numdiv(m))); \\ Antti Karttunen, Jan 22 2025

Formula

a(n) = A006218(n) - A143615(n).