A074112 - OEIS

%I #17 Jan 16 2019 04:13:46

%S 6,78,966,9870,99330,930930,9699690,99953490,999068070,9592993410,

%T 99978788910,999890501610,9814524629910,99999887777790,

%U 998448347106210,9999999768941490,99992911041433410,997799870344687410,9999839051940347610,99987077573596883670

%N Let omega(m) be the number of distinct prime divisors of m. Then a(n) is the largest n-digit squarefree number such that omega(n) > omega(j) for all j < n.

%H Charlie Neder, <a href="/A074112/b074112.txt">Table of n, a(n) for n = 1..33</a>

%H Charlie Neder, <a href="/A074112/a074112.py.txt">Python program for computing this sequence</a>

%p A074112 := proc(n)

%p     option remember;

%p     local a,o,wrks,j ;

%p     if n = 1 then

%p         return 6;

%p     end if;

%p     for a from 10^n-1 to 10^(n-2) by -1 do

%p         if numtheory[issqrfree](a) then

%p             o := omega(a) ;

%p             wrks := true;

%p             for j from 1 to n-1 do

%p                 if omega(procname(j)) >= o then

%p                     wrks := false;

%p                     break;

%p                 end if;

%p             end do:

%p             if wrks then

%p                 return a;

%p             end if;

%p         end if;

%p     end do:

%p     return -1 ;

%p end proc:

%p for j from 1 do

%p     print( A074112(j)) ;

%p end do: # _R. J. Mathar_, Oct 03 2014

%Y Cf. A002110, A074111.

%K base,nonn

%O 1,1

%A _Amarnath Murthy_, Aug 27 2002

%E Corrected and extended by _Matthew Conroy_, Aug 27 2002

%E Definition corrected by _R. J. Mathar_, Oct 03 2014

%E a(8) to a(20) from _Charlie Neder_, Jan 15 2019