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.

6, 78, 966, 9870, 99330, 930930, 9699690, 99953490, 999068070, 9592993410, 99978788910, 999890501610, 9814524629910, 99999887777790, 998448347106210, 9999999768941490, 99992911041433410, 997799870344687410, 9999839051940347610, 99987077573596883670

Offset: 1

Author

Amarnath Murthy, Aug 27 2002

Keywords

• base
• nonn

Links

• Charlie Neder, Table of n, a(n) for n = 1..33
• Charlie Neder, Python program for computing this sequence

Crossrefs

Cf. A002110, A074111.

Programs

Maple

A074112 := proc(n)
    option remember;
    local a,o,wrks,j ;
    if n = 1 then
        return 6;
    end if;
    for a from 10^n-1 to 10^(n-2) by -1 do
        if numtheory[issqrfree](a) then
            o := omega(a) ;
            wrks := true;
            for j from 1 to n-1 do
                if omega(procname(j)) >= o then
                    wrks := false;
                    break;
                end if;
            end do:
            if wrks then
                return a;
            end if;
        end if;
    end do:
    return -1 ;
end proc:
for j from 1 do
    print( A074112(j)) ;
end do: # R. J. Mathar, Oct 03 2014

Extensions

Corrected and extended by Matthew Conroy, Aug 27 2002

Definition corrected by R. J. Mathar, Oct 03 2014

a(8) to a(20) from Charlie Neder, Jan 15 2019