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%I #4 Jan 16 2013 07:59:03
%S 23,31,71,113,131,167,271,293,317,347,359,373,379,389,491,571,631,673,
%T 677,719,761,773,811,877,911,929,937,941,971,983,997,1031,1091,1103,
%U 1171,1193,1223,1231,1283,1291,1361,1409,1433,1511,1523,1531,1571,1607
%N Primes that appear as a substring in the concatenation of primes.
%C Start with a blank concatenation string S. Does prime p(1)=2 appear in string S? No. Concatenate 2 to string S. Does prime p(2)=3 appear in string S="2"? No. Concatenate 3 to string S. Does prime p(3)=5 appear in string S="23"? No. Concatenate 5 to string S. and so on Does prime p(9)=23 appear in string S="235711131719"? Yes. 23 is in the sequence. Do not concatenate 23 to string S.
%e a(1)= 23 because 23 appears in the string 235711131719. a(3)= 71 because 71 appears in the string 235711131719293741434753596167. (Notice "23" is omitted from the string here: 235711131719--293741434753596167.)
%K easy,nonn,base
%O 1,1
%A _Gil Broussard_, Jan 19 2009