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%I #2 Dec 05 2013 19:56:31
%S 0,2,3,43,5,0,7,0,0,109,11,0,13,0,0,0,17,0,19,0,0,2221,23,2423,
%T 25242322212019181716151413,0,2726252423,0,29,0,31,0,0,3433,0,0,37,0,
%U 0,0,41,4241,43,0,0,4645444342414039,47,4847464544434241,0,0,5150494847
%N Smallest prime which has the form of the concatenation n, n-1, n-2, n-3, .., n-k for some k < n, or 0 if no such prime exists.
%C a(p) = p. Conjecture; There are infinitely many composite numbers n such that a(n) is nonzero.
%e a(10) = 109 a concatenation of 10 and 9.
%e a(6) = 0 as no number in the sequence 6,65,654,6543,65432,654321 is prime.
%K base,nonn
%O 1,2
%A _Amarnath Murthy_, Sep 16 2003
%E Corrected and extended by Gabriel Cunningham (gcasey(AT)mit.edu), Sep 21 2003