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%I #20 May 14 2022 16:05:36
%S 1,2,3,4,5,7,11,14,17,19,23,31,34,37,38,41,43,47,49,51,53,57,59,62,67,
%T 69,71,73,74,79,83,85,86,89,93,94,97,101,103,106,109,113,115,118,119,
%U 129,134,137,139,141,142,146,149,151,157,159,163
%N Prime factors of repunit of length a(n) are all of different lengths.
%H Max Alekseyev, <a href="/A046420/b046420.txt">Table of n, a(n) for n = 1..117</a> (first 107 terms from Ray Chandler)
%H P. De Geest, <a href="http://www.worldofnumbers.com/repunits.htm">Repunits prime factors</a>
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/Repunit.html">Repunit</a>
%e a(n)=14 -> 11*239*4649*909091 -> (2)(3)(4)(6) all of different lengths.
%t Select[Range[60],Length[fi=FactorInteger[(10^#-1)/9]]== Plus@@Last/@fi==Length[Union[IntegerLength/@First/@fi]]&] (* _Ray Chandler_, Apr 24 2017 *)
%Y Cf. A000042, A004022, A046053.
%K nonn,base
%O 1,2
%A _Patrick De Geest_, Jul 15 1998
%E Offset changed to 1 and more terms added by _Ray Chandler_, Apr 24 2017
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