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Search: id:A140382
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| A140382 |
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Prime pairs of the form (p,p+4). |
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+0
4
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| 3, 7, 7, 11, 13, 17, 19, 23, 37, 41, 43, 47, 67, 71, 79, 83, 97, 101, 103, 107, 109, 113, 127, 131, 163, 167, 193, 197, 223, 227, 229, 233, 277, 281, 307, 311, 313, 317, 349, 353, 379, 383, 397, 401, 439, 443, 457, 461, 463, 467, 487, 491, 499, 503, 613, 617
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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The two primes p and p+4 are not necessarily adjacent.
Removal of duplicates yields A094343. [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Aug 27 2008]
p*(p+4)+4 is square [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Oct 27 2009]
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FORMULA
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a(2n-1)=A023200(n). a(2n)=A046132(n).
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EXAMPLE
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The pairs are (3,7), (7,11), (13,17) etc.
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CROSSREFS
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Cf. A000040.
Sequence in context: A020764 A010625 A011322 this_sequence A080457 A119644 A109386
Adjacent sequences: A140379 A140380 A140381 this_sequence A140383 A140384 A140385
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KEYWORD
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nonn,less,new
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AUTHOR
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Juri-Stepan Gerasimov (2stepan(AT)rambler.ru), Jun 14 2008
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EXTENSIONS
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Edited by R. J. Mathar, Jun 16 2008
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