%I A075023
%S A075023 1,11,3,11,41,3,239,11,3,12345678910987654321,7,3,1109,7,3,71,7,3,251,
               7,
%T A075023 3,70607,7,3
%N A075023 a(1) = 1, a(n) = the smallest prime divisor of the number C(n) = concatenation 
               of 1,2,3... up to n then reverse up to 1.
%e A075023 a(5) = 41 as 123454321= 41*41*271*271.
%Y A075023 Cf. A075019, A075020, A075021, A075022, A075024.
%Y A075023 Sequence in context: A110435 A110774 A067063 this_sequence A088262 A110406 
               A110434
%Y A075023 Adjacent sequences: A075020 A075021 A075022 this_sequence A075024 A075025 
               A075026
%K A075023 base,nonn
%O A075023 1,2
%A A075023 Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Sep 01 2002
%E A075023 More terms from Sascha Kurz (sascha.kurz(AT)uni-bayreuth.de), Jan 03 
               2003