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Search: id:A151740
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| A151740 |
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Composite which are the sum of two consecutive composite numbers. |
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+0
5
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| 10, 14, 22, 26, 34, 38, 46, 49, 51, 55, 58, 62, 65, 69, 74, 77, 82, 86, 91, 94, 99, 106, 111, 115, 118, 122, 125, 129, 134, 142, 146, 153, 155, 158, 161, 166, 169, 171, 175, 178, 183, 185, 187, 189, 194, 202, 206, 209, 214, 218, 221, 226, 231, 235, 237, 243, 245
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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The even terms of this sequence are exactly twice the primes > 3. The odd terms are odd composites c for which the odd integer next to c/2 is not prime. [From M. F. Hasler (MHasler(AT)univ-ag.fr), Jun 16 2009]
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MATHEMATICA
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CompositeNext[n_]:=Module[{k=n+1}, While[PrimeQ[k], k++ ]; k]; q=6!; lst2={}; Do[If[ !PrimeQ[n], c=CompositeNext[n]; a2=n+c; If[ !PrimeQ[a2], AppendTo[lst2, a2]]], {n, q}]; lst2 [From Vladimir Orlovsky (4vladimir(AT)gmail.com), Jun 17 2009]
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PROGRAM
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(PARI) isA151740(n)={ bittest(n, 0) | return(isprime(n/2) & n>6); !isprime(bitor(n\2, 1)) & !isprime(n) & n>1 } [From M. F. Hasler (MHasler(AT)univ-ag.fr), Jun 16 2009]
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CROSSREFS
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Cf. A151741-A151745, A060254, A060327, A060339, A096785, A096787, A135170. [From M. F. Hasler (MHasler(AT)univ-ag.fr), Jun 16 2009]
Sequence in context: A063764 A138511 A167611 this_sequence A136802 A084278 A069207
Adjacent sequences: A151737 A151738 A151739 this_sequence A151741 A151742 A151743
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KEYWORD
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nonn
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AUTHOR
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Claudio L Meller (claudiomeller(AT)gmail.com), Jun 15 2009
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