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Search: id:A036931
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| A036931 |
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Smallest n-digit prime containing only digits 1 and 4, or 0 if no such prime exists. |
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+0
2
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| 0, 11, 0, 4111, 11411, 0, 1114111, 11111141, 0, 1111111411, 11111141411, 0, 1111111111441, 11111111111411, 0, 1111111111114441, 11111111111414411, 0, 1111111111111111111, 11111111111111414441, 0, 1111111111111111144141
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OFFSET
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1,2
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COMMENT
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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
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FORMULA
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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
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CROSSREFS
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Cf. A036229, A020452, A036304.
Cf. A004022 (repunit primes), A004023.
Sequence in context: A075361 A073864 A073865 this_sequence A165399 A157712 A158215
Adjacent sequences: A036928 A036929 A036930 this_sequence A036932 A036933 A036934
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KEYWORD
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nonn,base
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AUTHOR
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Patrick De Geest (pdg(AT)worldofnumbers.com), Jan 04 1999.
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EXTENSIONS
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More terms from Rick L. Shepherd (rshepherd2(AT)hotmail.com), Feb 08 2004
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