%I #10 May 01 2018 02:44:47
%S 11,241,1231,71421281,2468101,246810121,244872961201441681,
%T 8162432404856641,1234567891,10320630941251561872182492710301,
%U 12345678910111,12243648607284961081201321441,43861291722152583013443874304735165591,9418828237647056465875284694010341128122213161,214263841051261471681892102312522732943151
%N Smallest prime of the form the concatenation r*k for r = 1 to n followed by a 1.
%H Robert Israel, <a href="/A089328/b089328.txt">Table of n, a(n) for n = 1..187</a>
%e a(3) = 1231 and k = 1.
%p dcat:= proc(L) local t,i;
%p t:= L[1];
%p for i from 2 to nops(L) do
%p t:= t*10^(1+ilog10(L[i]))+L[i]
%p od:
%p t
%p end proc:
%p f:= proc(n) local r,k,p;
%p for k from 1 do
%p p:= dcat([seq(r*k,r=1..n),1]);
%p if isprime(p) then return p fi
%p od
%p end proc:
%p map(f, [$1..20]); # _Robert Israel_, Apr 30 2018
%Y Cf. A089329.
%K base,nonn
%O 1,1
%A _Amarnath Murthy_, Nov 04 2003
%E More terms from _David Wasserman_, Sep 13 2005