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A099047
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Numbers n such that n-1 and n+1 are both composite.
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1
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5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 25, 26, 27, 29, 31, 33, 34, 35, 37, 39, 41, 43, 45, 47, 49, 50, 51, 53, 55, 56, 57, 59, 61, 63, 64, 65, 67, 69, 71, 73, 75, 76, 77, 79, 81, 83, 85, 86, 87, 89, 91, 92, 93, 94, 95, 97, 99, 101, 103, 105, 107, 109, 111, 113, 115, 116, 117
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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MATHEMATICA
| Select[Range[6! ], !PrimeQ[ #-1]&&!PrimeQ[ #+1]&] [From Vladimir Orlovsky (4vladimir(AT)gmail.com), Apr 26 2010]
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PROG
| (PARI) for(n=5, 200, if(!isprime(n-1)&&!isprime(n+1), print1(n, ", ")))
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CROSSREFS
| Sequence in context: A168146 A106505 A097985 * A174392 A084926 A049013
Adjacent sequences: A099044 A099045 A099046 * A099048 A099049 A099050
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KEYWORD
| nonn
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AUTHOR
| Rick L. Shepherd (rshepherd2(AT)hotmail.com), Nov 13 2004
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