%I A036931
%S A036931 0,11,0,4111,11411,0,1114111,11111141,0,1111111411,11111141411,0,
%T A036931 1111111111441,11111111111411,0,1111111111114441,11111111111414411,0,
%U A036931 1111111111111111111,11111111111111414441,0,1111111111111111144141
%N A036931 Smallest n-digit prime containing only digits 1 and 4, or 0 if no such 
               prime exists.
%C A036931 For any positive integer k, a(3k) = 0 as any 3k-digit number containing 
               only digits 1 or 4 or both has a digit-sum divisible by 3 and thus 
               the number is divisible by 3. - Rick L. Shepherd (rshepherd2(AT)hotmail.com), 
               Feb 08 2004
%F A036931 a(3k) = 0 and a(A004023(k)) = (10^A004023(k) - 1)/9 = A004022(k) for 
               all positive integers k. - Rick L. Shepherd (rshepherd2(AT)hotmail.com), 
               Feb 08 2004
%Y A036931 Cf. A036229, A020452, A036304.
%Y A036931 Cf. A004022 (repunit primes), A004023.
%Y A036931 Sequence in context: A075361 A073864 A073865 this_sequence A165399 A157712 
               A158215
%Y A036931 Adjacent sequences: A036928 A036929 A036930 this_sequence A036932 A036933 
               A036934
%K A036931 nonn,base
%O A036931 1,2
%A A036931 Patrick De Geest (pdg(AT)worldofnumbers.com), Jan 04 1999.
%E A036931 More terms from Rick L. Shepherd (rshepherd2(AT)hotmail.com), Feb 08 
               2004