A063875 Numbers k such that sigma(k) - usigma(k) > 3k.

831600, 1058400, 1587600, 1663200, 1814400, 1940400, 1965600, 2116800, 2328480, 2494800, 2570400, 2646000, 2721600, 2872800, 2910600, 2948400, 3024000, 3175200, 3326400, 3528000, 3603600, 3628800, 3704400, 3880800, 3931200

Offset: 1

Author

Jason Earls, Aug 27 2001

Keywords

• nonn

Links

• Harry J. Smith, Table of n, a(n) for n = 1..400

Crossrefs

Cf. A034448, A048146, A034683, A063846.

Programs

PARI

u(n) = sumdiv(n,d, if(gcd(d,n/d)==1,d));
for(n=1,10^9, if(sigma(n)-u(n)>3*n,print(n)))

PARI

u(n) = sumdiv(n, d, if(gcd(d, n/d)==1, d))
{ n=0; for (m=1, 10^9, if(sigma(m) - u(m) > 3*m, write("b063875.txt", n++, " ", m); if (n==1000, break)) ) } \\ Harry J. Smith, Sep 01 2009

Extensions

a(20)-a(25) from Harry J. Smith, Sep 01 2009