cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A074112 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.

This page as a plain text file.
%I A074112 #17 Jan 16 2019 04:13:46
%S A074112 6,78,966,9870,99330,930930,9699690,99953490,999068070,9592993410,
%T A074112 99978788910,999890501610,9814524629910,99999887777790,
%U A074112 998448347106210,9999999768941490,99992911041433410,997799870344687410,9999839051940347610,99987077573596883670
%N A074112 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 A074112 Charlie Neder, <a href="/A074112/b074112.txt">Table of n, a(n) for n = 1..33</a>
%H A074112 Charlie Neder, <a href="/A074112/a074112.py.txt">Python program for computing this sequence</a>
%p A074112 A074112 := proc(n)
%p A074112     option remember;
%p A074112     local a,o,wrks,j ;
%p A074112     if n = 1 then
%p A074112         return 6;
%p A074112     end if;
%p A074112     for a from 10^n-1 to 10^(n-2) by -1 do
%p A074112         if numtheory[issqrfree](a) then
%p A074112             o := omega(a) ;
%p A074112             wrks := true;
%p A074112             for j from 1 to n-1 do
%p A074112                 if omega(procname(j)) >= o then
%p A074112                     wrks := false;
%p A074112                     break;
%p A074112                 end if;
%p A074112             end do:
%p A074112             if wrks then
%p A074112                 return a;
%p A074112             end if;
%p A074112         end if;
%p A074112     end do:
%p A074112     return -1 ;
%p A074112 end proc:
%p A074112 for j from 1 do
%p A074112     print( A074112(j)) ;
%p A074112 end do: # _R. J. Mathar_, Oct 03 2014
%Y A074112 Cf. A002110, A074111.
%K A074112 base,nonn
%O A074112 1,1
%A A074112 _Amarnath Murthy_, Aug 27 2002
%E A074112 Corrected and extended by _Matthew Conroy_, Aug 27 2002
%E A074112 Definition corrected by _R. J. Mathar_, Oct 03 2014
%E A074112 a(8) to a(20) from _Charlie Neder_, Jan 15 2019