A214443 - OEIS

%I #13 Aug 08 2012 15:35:52

%S 5,77,233415,105411381075

%N Least number k such that (sum of anti-divisors of k)/k >= n.

%C Least number k such that A066417(k)/k >= n.

%H Jon Perry, <a href="/A066272/a066272a.html">The Anti-divisor</a>

%o (PARI) a066417(n)=local(x); x=valuation(n, 2); sigma(2*n+1)+sigma(2*n-1)+sigma(n/2^x)*2^(x+1)-6*n-2

%o for(n=1, 3, for(k=3, 233415, if(a066417(k)/k>=n, print(n " " k); next(2))))

%Y Cf. A066272, A066417.

%K nonn,more

%O 1,1

%A _Donovan Johnson_, Aug 08 2012