A109942 Largest k-digit number coprime to n, where k is the number of digits in n.

9, 9, 8, 9, 9, 7, 9, 9, 8, 99, 98, 97, 99, 99, 98, 99, 99, 97, 99, 99, 97, 97, 99, 97, 99, 99, 98, 99, 99, 97, 99, 99, 98, 99, 99, 97, 99, 99, 98, 99, 99, 97, 99, 97, 98, 99, 99, 97, 99, 99, 98, 99, 99, 97, 98, 99, 98, 99, 99, 97, 99, 99, 97, 99, 99, 97, 99, 99, 98, 99, 99, 97

Offset

1,1

Links

Robert Israel, Table of n, a(n) for n = 1..10000

Formula

a(n) >= n+1 unless n is in A002283, in which case a(n)=n-1. - Robert Israel, Jan 30 2017

Maple

f:= proc(n) local k;
      for k from 10^(1+ilog10(n))-1 by -1 do
         if igcd(n, k) = 1 then return k fi
      od
end proc:
map(f, [$1..100]); # Robert Israel, Jan 30 2017

Crossrefs

Sequence in context: A050812 A139345 A231470 * A339745 A346929 A346927

Adjacent sequences: A109939 A109940 A109941 * A109943 A109944 A109945

Keyword

base,easy,nonn

Author

Amarnath Murthy, Jul 19 2005

Extensions

More terms from David Wasserman, Jul 19 2005

Status

approved