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Search: id:A085080
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| A085080 |
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Smallest k such that n, k and n+k have the same prime signature (canonical form), or 0 if no such number exists. |
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+0
1
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| 0, 3, 2, 0, 2, 15, 0, 0, 0, 55, 2, 63, 0, 21, 6, 0, 2, 45, 0
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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1. a(n) = 0 if n is a perfect prime power or a prime such that n+2 is composite. The zero entries in other cases suggest a generalization of Fermat's last theorem. a(n) = 2 if n and n+2 form a twin prime pair.
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EXAMPLE
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a(12) = 63 as 12 + 63 = 75, 2^2*3 + 3^2*7 = 5^2*3, all have the prime signature p^2*q.
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CROSSREFS
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Sequence in context: A077814 A131728 A075115 this_sequence A079714 A114907 A131732
Adjacent sequences: A085077 A085078 A085079 this_sequence A085081 A085082 A085083
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KEYWORD
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more,nonn
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AUTHOR
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Amarnath Murthy and Meenakshi Srikanth (amarnath_murthy(AT)yahoo.com), Jul 01 2003
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