cp's OEIS Frontend

A070844 a(n) = smallest n-digit number with exactly n divisors, or 0 if no such number exists.

%I A070844 #10 Dec 05 2013 19:55:19
%S A070844 1,11,121,1003,14641,100017,1771561,10000005,100020001,1000000016,
%T A070844 25937424601,100000000004,3138428376721,10000000001344,
%U A070844 100000720001296,1000000000000006,45949729863572161,100000000000000404
%N A070844 a(n) = smallest n-digit number with exactly n divisors, or 0 if no such number exists.
%H A070844 Ray Chandler, <a href="/A070844/b070844.txt">Table of n, a(n) for n=1..41</a>
%F A070844 If n is a prime < 29 then a(n) = 11^(n-1). - Chandler
%F A070844 If n is a prime >= 29 then a(n) = 0. - _Vladeta Jovovic_, Aug 20 2002
%t A070844 For[n=1, n<10, n++, k := 10^(n-1); While[Not[Length[Divisors[k]] == n], k++ ]; Print[k]] (Steinerberger)
%Y A070844 Cf. A070845.
%K A070844 base,nonn
%O A070844 1,2
%A A070844 _Amarnath Murthy_, May 12 2002
%E A070844 a(6)-a(18) from _Vladeta Jovovic_, Aug 20 2002
%E A070844 a(6) confirmed by Antonio G. Astudillo (afg_astudillo(AT)lycos.com), Apr 08 2003
%E A070844 a(7)-a(10) confirmed by _Stefan Steinerberger_, Feb 06 2006
%E A070844 a(15) corrected, and a(11)-a(14), a(16)-a(18) confirmed by _Ray Chandler_, Feb 10 2009
%E A070844 Edited by _N. J. A. Sloane_, Feb 14 2009 at the suggestion of Ray Chandler.